US1074150A - Process of treating materials. - Google Patents

Description

FREDERICK YOST, OF CHICAGO, ILLINOIS.

PROCESS OF TREATING- MATERIALS.

Specification of Letters Patent.

Patented Sept. 30, 1913.

No Drawing. Application filed April 11, 1910, Serial No. 554,712. Renewed February 19, 1913. Serial To all whom it may concern I Be it known that I, FREDERICK W. Yosr, a citizen of the United States, residing at Chicago, in the county of Cook and State dust, iron ore concentrates and other similar materials are advantageously clinkered to fit them for use in the blast furnace, and when these materials have a high sulfur content they also require roasting. For special metallurgical purposes 'it may be desirable to reduce these materials to lower oxide of iron or to sponge iron. Sulfid ores are roasted to partially or wholly convert them into oxids tomeet the requirements of various smelting and refining operations. Sulfid ore fines or concentrates require clinkering to adapt them for smelting in stack furnaces and to avoid the more expensive method of smelting in reverberatory furnaces. Materails like chrome ore, magnesite, bauxite and clay, are calcined to eliminate chemically combined water or carbon dioxid. Finely ground mixtures of clay and limestone or suit-able equivalents of these materials, are calcined and clinkered to make cement clinker. In my prior applications, Serial Number 501,561 filed June 11, 1909, and Serial Numbers 516,305 and 516,306, filed September tth, 1909, renewed J an. 16, 1911, Serial Nos. 602,978, 602,979and 602,980, respectively', I describe and claim processes which comprise forming such material into a mass adapted for the propagation of one or more of the described reactions, initiating a reaction at a surface of the mass, conducting a reactionproducing or reaction-supporting gas through the mass toward the surface of initial reaction, and by suitable control of conditions propagating one or more ofthe described reactions through the mass in one or more directions. In these prior processes a stationary or movable mass of material is usually heated at theupper surface by a body of hot furnace'gases, and a current of air is usually conducted upward through the mass; and under these conditions the waste gases of reaction containing a large amount of heat, escape at the upper surface and join the furnace gases Which are at a relatively high temperature when they leave the furnace. The utilization of this waste heat, by conducting all or part of the furnace gases through the mass of material being treated, during one stage of the treatment, is one of the principal objects of the present invention. In the present invention the reaction-producing or reactionsupporting gases are conducted through the charge in two currents moving in diflerent directions, and the independent control of each gas current as to composition, pressure and temperature, results in a great variety of operating methods eachof which is particularly adapted to the special requirements of some material.

The adaptability of modified forms of the process to the special requirements ofmany materials and to various special treatments of material, constitutes another important object of the invention.

My invention relates to the treatmentof materials; and it comprises a process where in two currentsof reaction-producing or reaction-supporting gas are conducted through a mass of materialin different directions, under conditions that cause one or more reactions to beinitiated in the mass and to be ducted in one direction through a stationary or movable mass of finely divided material, 1

and a combustion-supporting gas is conducted through the mass in another direction, under such conditions that both a heating zone and a clinkering reaction are propagated separately or conjointly through the mass in one or more directions; all as more fully hereinafter set forth and as claimed.

In the older forms of the pot roasting process heat is applied to the bottom of the charge, combustion is propagated upward by means of an air blast conducted'in the same direction, and the gases that escape from the charge disturb the particles of material at the upper surface, thereby preventingthe sintering of the material at that surface. Recent improvements in pot roasting processes are designed to prevent this disturbance of material at the gas exit surface of the charge, by applying the heat to the upper surface, and by conducting the blast of air and propagating the combustion downward toward the supporting grate, thus inverting the operation carried onin the older forms of pot roasting processes. During the entire period of operation, in the inverted pot roasting process, the waste gases escape from the charge by passing through the grates at a high temperature, and near the end of the operation the sintering action takes place in contact with the grates. The grates therefore are subjected to the combined destructive action of the highly heated waste gases, and of sintered material in a state of semi-fusion. In the present process the difiiculties encountered in all forms of pot roasting can be avoided. The heating gases may be conveniently introduced to the interior of the charge at the free and unrestrained upper surface, thereby preventing the movement of material at that surface. lVhile the heating gases are being conducted through the charge, a layer of cold material is usually maintained at the lower surface, so that the escaping gases pass through the grates at a relatively low temperature and without producing destructive effects. The lower portion of the charge is not clinkered while the waste heating gases escape through the grates, but instead this portion of the charge'is usually clinkered while a current of air or other reactionsupporting gas is passing upward through the charge, and the grates are therefore protected while in contact with fusing clinker, by the passage of a relatively cold air current. There is practically no separate control of the roast reaction in any pot roasting process, because the zone of sintering follows immediately after the zone of combustion, and therefore the composition of the finished product can be changed only by changing the composition of the raw material that. forms the charge.- The present process, in common with the processes described in my Jrior applications, has the great advantage 0. permitting independent control of the roasting and the clinkerin reactions, and therefore the composition of the finished product may be changed at will to suit various requirements.

My present process may be carried on in any form of pot roasting apparatus provided with a covered top or in any reverberatory roasting furnace provided with a perforated hearth, for the treatment of single masses or charges; or it can be carried. on in i a more or less continuous manner in well masses traveling continuously or intermittently through the furnace chamber. The particular form of apparatus used for carrying on this process, is not material to the terials of the mass, as by the mixing of powdered fuel with finely divided oxid'ores. For example, finely divided iron, copper, or other metallic sulfids high in sulfur and in the form of ores, concentrates, mattes, or flue dust, may be treated by my process without the addition of other fuel; or if low in sulfur, these materials may be mixed with a suitable finely divided fuel. As another example, finely divided iron oxid in the form of fine Mesaba ore or blast furnace flue dust, 7

may be mixed with powdered fuel such as bituminous coal screenings, coke breeze or anthracite coal dust, to form a mass adapted for treatment by my process; materlals intended for making Portland cement, such as pulverized mixtures of clay and limestone either naturally or artificially mixed, or partly naturally and partly artificially mixed, may be treated by my process by first adding to the material a finely divided fuel; or materials like chrome ore, magnesite, bauxite or clay,which by ordinary methods are not readily calcined, may be mixed with suitable fuel and treated'by my process in which the fine state of division and the intimate contact of the material with the fuel materially hastens the calcining operation. Many other materials which are capable of undergoing formed into a suitablemass, may betreated by my process, and I regard its application to all such materials as within the scope of my invention.

As a preferred embodiment of the inven- 7 tion, my process may be applied to the clinkering of finely divided iron oxid. This material may be a pulverous natural ore, the granular product of a concentration process, or a finely divided metallurgical waste such as blast furnace fiue dust or fine pyrites cinder. The fine iron oxid is mixed with powdered coal, coke, charcoal or other combustible material, and is charged into any suitable furnace ofone of the types referred to. Any fuel adapted for use in a reverberatcry furnace, maybe used to generate flame or furnace gases, which are conducted through the furnace in contact with the upper surface of the charge. A portion or preferably all of the furnace gases are conducted downward through the charge,

a propagative reaction when and through the perforated hearth or grate into a suitable outlet flue. During this stage of the process the charge is heated uniformly and progressively from the top toward the bottom. Just before the material adjacent to the perforated hearth becomes red hot, a current of air, introduced through the perforated hearth, replaces the downward current of furnace gases and is conducted upward through the charge. A clinkering reaction is initiated in the lower part of the charge by the action of the air upon the heated material, and this clinkering reaction is propagated upward through the mass to the upper surface. The action of the air upon the heated material of the charge also propagates both a combustion and a clinkering reaction, through the layer of cold material adjacent to the perforated hearth. The volatile products of internal combustion together with the excess of air required for clinkering, escape at the upper surface of the charge and join the furnace gases. When this form of theprocess is carried on discontinuously in a reverberatory furnace with a fixed perforated hearth, the waste gases escaping from the charge during the clinkering stage may be conducted from the furnace chamber through an outlet flue; or they may be conducted through a suitable flue into another similar furnace and there may .be conducted downward through another similarcharge, thus utilizing the sensible heat of the waste gases for heating the second charge. In any fixed hearth furnace this form of the process is carried on by first conducting the furnace gases downward through thech'arge until the desired amount of heating is secured, and the upward propagation of the clinkering reaction does not begin until the downward current'of furnace gases is discontinued and an upward current of air replaces the downward current of furnace gases. This form of the process may also be carried on in a chain grate stoker type of furnace or in any other type of movable perforated-hearth furnace by alternately conducting the downward gas current and the upward gas current through the charge and by holding the charge at rest during the time of treatment, the charge being moved out of the furnace chamber when the clinkering stage of the process is completed. Another method of operating in a chain grate stolrer type of furnace or in any other type of movable perforated-hearth furnace consists in continuously conducting the downward gas current through the charge in one part of the'furnace and C011, tinuously conducting the upward gas current through the charge in another part of j the furnace, holding the charge at rest while one portion is being heated and another portion is being clinkered, and then moving the hearth so'as to carry the heatedportion of i the charge into the clinkering region of the furnace and the clinkered portion out of the furnace chamber. When the material is treated continuously in a chain grate stoker type of furnace, by moving the hearth in a more or less continuous manner, the various stages of the operation take place simultaneously in different parts of the furnace. In one part of the furnace the furnace gases are continuously conducted downward through the moving charge while in another part of the furnace a current of air is continuously conducted upward through the moving charge. Near the entrance end of the furnace the moving mass of material is continuously heated by conducting the furnace gases downward through the charge, while near the eXit end of the furnace the moving mass of heated material is continuously clin kered by conducting a current of air upward through the charge. Under these conditions, the furnace gases are continuously generated by the combustion of extraneous fuel, and the highly heated waste gases escaping from the charge at the clinkering end of the furnace and containing a large excess of air, supply the greater portion of the air required for the generation and combustion of the furnace gases. When operating in this continuous manner and when the two gas currents are utilized as described, this process realizes the highest attainable thermal efficiency; because the hot clinker serves as a regenerator to heat the upward current of air, which after its escape from the charge is used for the combustion of the furnace gases, while the coldportion of the charge acts as a regenerator to absorb the greater part of the heat in the downward current of outgoing furnace gases.

During the heating stage of the process, the upper surface of the charge may be slightly reduced by the furnace gases and partly fused to form a layer of clinker, which will prevent the disturbance of material at that surface during the clinkering stage. By properly regulating the composition and temperature of the furnace gases con-ducted downward through the charge, and by maintaining these conditions during the heating stage, the zone of clinker may be propagated downward through the upper portion of the charge during the heating stage; but the downward current of furnace gases must be replaced by the upward current of air while a relatively. thick layer of cold material still remains adjacent to the perforated hearth, to absorb the great heat generated in the clinkering zone. The

upward current of air acting on the heated material, propagates heat downward and a clinkering reaction upward, through the unclinkered lower portion of the charge. If preferred a layer of crushed limestone, clinker or similar material may be interposed between the perforated hearth and the material of the charge, to cool the clownward current of outgoing waste gases to a safe temperature before its passage through the perforated hearth. Under these conditions, the charge may be heated down to the lower surface with the downward current of furnace gases, and the heat absorbed by the protective layer of limestone or clinker, will be usefully employed during the second stage of the process in pre-heating the upward air current. YVhether clinker is formed by the action of both gas currents or whether it is formed only by the action of the upward air current, the carbonaceous material in the charge need only be sufficient in amount to cause the clinkering reaction to be initiated and propagated, since the charge is heated up to the reaction temperature in either case by the furnace gases. Under some conditions it may be desirable to conduct highly reducing furnace gases through the charge during the heating stage, and to cause these gases to deposit soot in the interstices of the mass, to serve as the fuel required for initiating and propagating the clinkering reaction. The carbonaceous components in the charge may also be decreased in quantity or may be wholly eliminated, by adding combustible gas to the air conducted through the charge. 'When it is desired to produce clinker containing the lower oxide of iron, or wholly reduced metal such as sponge iron, it is necessary to maintain more highly reducing conditions within the charge than those required for the production of high oxid clinker. Such highly reducing conditions may be secured by the use of larger pro-portions of carbonaceous material in the char e, with or without the addition of combustible gas to the upward air current. The finished product may be made into large and relatively dense blocks of clinker such as are desirable for open hearth furnace use, or into highly porous and relatively small pieces of clinker such as are desirable for blast furnace use, by varying the conditions under which the several stages ofthe process are conducted or by varying the composition of the charge.

My process may also be used for roasting and clinkering finely divided sulfid ores, concentrates or flue dust. The finely divided sulfur bearing material is charged into one of the types of furnace referred to, and furnace gases generated by the combustion of a suitable fuel, are conducted downward through the charge and escape through the perforated hearth or grate into a suitable outlet flue. During this stage of the operation the charge is heated and if desired it may also be roasted by the use of oxidizing furnace gases to remove any excess of sulfur. Before the zone of heat reaches the lower surface of the charge and" while there still remains a layer of relatively cold material adjacent to the perforated hearth, a current of air, introduced through the perforated hearth, replaces the downward current of furnace gases and conducted upward through the mass to imtiate a clinkering reaction in the heated material,and to propagate this clinkering reaction upward through the charge; The upward current of air acting on the heated material, also propagates a heating and a clinkering zone through the layer of cold material adjacent to the perforated hearth. The volatile products of combustion together with the excess of air employed for clinkering, escape from the upper surface of the charge and join the furnace gases.

During the heating stage of the process the upper surface of the charge may be fused to form a clinkered layer, which will prevent the disturbance of material at that surface during the clinkering stage. When the charge is sufficiently high in sulfur, this zone of clinker may be propagated downward through the upper portion of the charge during the heatingstage by properly regulating the temperature and composition of the furnace gases. When it 1s desired durin the heatin sta e to clinker h h b 7 the upper portion of a charge relatively low in sulfur, the downward current of furnace gases must be maintained at a high temperature, or a suitable quantity of other combustible material must be added to the charge. hen the furnace chamber is once heated to its working temperature, ores and concentrates containing a large, amount of sulfur, may be treated by this process without the use of an igniting flame generated by the combustion of eXtraneous fuel; because the heat radiated fro-m the furnace walls maintains the temperature of reaction during the clinkering stage, and the *aste gases of reaction maintain the temperature of the furnace and heat the charge. Under these conditions, the waste gases reach the outlet flue uncontaminated by products of combustion from carbonaceous fuel, and they are therefore rich in sulfur dioXid and are well suited for sulfuric acid manufacture'or other by-product purposes \Vhen the charge is too low in sulfur to' maintain the working'temperature of the furnace, and when a relatively rich gas is nevertheless desired for by-product use, heat from the combustion'of extraneous fuel may be transmitted to the charge through muffle walls. When the material to be treated is too low in sulfur for the propagation. of a clinkering reaction, other combustible elements may be added to the charge Since the heating and clinkering functions can be divided into separate stages, each of :which is subject to independent control,

- clinker of either-high or low sulfurcontent may beproducedat will to suit the requirements of subsequent smelting operations.

When this process is applied to the clinkering of cement materials, the finely ground raw mix is intimately mixed with powdered carbonaceous material, such as coal, coke or charcoal, and is charged into a suitable furnace of one of the'types described. The charge is heated and calcined by the downward current of furnace gases, and then clinkered by the action of the upward air current. By suitable control of conditions the upper portion of the charge may be clinkered during the'heating stage of the process. Cement materials may be clinkered by this process in a fixed hearth furnace, or in a furnace of the chain grate stoker type, and the method of operation may be similar in a general way to that used for making iron ore clinker.

All the embodiments-ofthis invention are characterized by the use of twogas currents conducted through the charge in clifferent directions; but all the other constituent features of the rocess are capable of numerous variations, .so that many specific operations and results are comprised in the invention. The composition and temperature of the current of furnace gases may be varied between wide limits, and it may be conductedthrough the charge in the first or second stage of the process; the current of airmay be hot or cold, diluted or undiluted, and it may be conducted, at widely varying pressures, through the charge in the first or second stage of the process, Thefurnace gases maybe used only for heating the upper surface of the charge, and currents of air suitably controlled in composition, temperature and pressure, may be conducted through the charge in both stages of the process. The process may be otherwise modified by changing the composition and the porosity of the charge. JV hen the operation is carriedon more or less continuously in a chain grate stoker type of furnace, the process may be further modified by changing the location, in the length of the furnace chamber, of the flame gas inlet; and the process may be then still further modified, by conducting these gases through the furnace chamber in the same direction as that of the moving charge, or in the opposite direction. During the first stageof the process, an upward or a downward current, of either air or furnace gases, may be used under suitable conditions of control, to propagate the zone of heat downward through the charge, accompanied or unaccompanied by a clinkering reaction.

Likewise in thesecond stage of the process underproper control of co-ndlt-lons, a current OffilI or of furnace gases, mov ng either upward or downward, may beused to propagate a heating zone through any remaining unheated portion of the charge, and to propagate the clinkering reaction either upward or downward, through the unclinkered portion of the charge.

In one specific method of operating in a fixed hearth furnace, a zone of heat is propagated downward from the upper surface by conducting furnace gases downward through the charge. The composition and temperature of the furnace gases are so controlled, that no clinkering reaction is initiated or propagated through the charge during the heating-stage. When the zone of heat reaches the lower surface of the charge, the downward current of furnace gases is dis continued and is replaced by an upward current of air which is used to initiate a clinkering reaction at the lower surface, and to propagate this clinkering reaction upward through the charge. In a second specific method of operating in a fixed hearth furnace, a zone of heat is propagated downward from the upper surface by conducting furnace gases downward through the charge. The composition and temperature of the furnace gases are so controlled, that a clinkering reaction is initiated at the upper surface and is propagated downward through the upper portion of the charge, but more slowly than the downward progress of the heating zone. When the zone of heat reaches the lower surface, the lower portion of the charge is composed of hot unclinkered material and the upper portion is composed of hot clinkered material. The downward current of furnace gases is now discontinued and is replaced by an upward current of air which is used to initiate a clinkering reaction at the lower surface, and to propagate this clinkering reaction upward through the unclinkered lower portion of the charge. In a third specific method of operating in a fixed hearth furnace, the upper surface of the charge is heated by furnace gases which are not conducted through the charge during the heating stage, but instead a current of air is conducted upward through the charge and is used to propagate a zone of heat downward from the upper surface. When the zone of heat reaches the lower surface of the charge, the upward current of air isdiscontinued and is replaced by a downward current of furnace gases which is used to initiate a clinkering reaction at the upper surface, and to propagate this clinkering reaction downward to the lower surface. In a fourth specific method of operating in a fixed hearth furnace, the upper surface of the charge is heated by furnace gases which are not conducted through the charge during the heating stage, but instead a current. of air is.- conducted upward through the charge and is used to propagate a zone of heat downward from the upper surface. By proper control of conditions, a clinkering reaction is initiated at the upper surface and is propagated downward through the upper portion of the charge during the heating stage, but more slowly than the downward progress of the heating zone. lVhen the zone of heat reaches the lower surface, the upper portion of the charge is composed of clinkered material and the lower portion is composed of hot unclinkered material. The upward air current is now discontinued and is replaced by a downward current of furnace gases which is used to propagate the clinkering reaction downward through the unclinkered lower portion of the charge. In a fifth specific method of operating in a fixed hearth furnace, a zone of heat is propagated downward from the upper surface by conducting furnace gases downward through the charge. The composition and temperature of the furnace gases are so controlled, that a clinkering reaction is initiated at the upper surface and is propagated downward through the upper portion of the charge during the heatstage, but more slowly than the downward progress of the heating zone. The downward current of furnace gases is discontinued and is replaced by an upward air current before the zone of heat reaches the lower surface of the charge, and while a relatively thick layer of cold material remains adjacent to the perforated hearth. hen the gas currents are reversed, the upper portion of the charge is composed of clinkered material, the intermediate portion is composed of hot unclinkered material, and the lower portion is composed of unheated material. The upward current of air isused to propagate the zone of heat downward through the unheated portion of the charge, and to propagate the clinkeriug reaction downward through the unclinkeredportion of the charge. In a sixth specific method of operating in a fixed hearth furnace, a zone of heat is propagated downward from the upper surface by conducting furnace gases downward through the charge. The downward current of furnace gases is dis continued and is replaced by an upward air current before the zone of heat reaches the lower surface of the charge, and while a layer of cold material remains adjacent to the perforated hearth. The upward current of air is used to propagate the zone of heat downward through the unheated lower portion of the charge, and to propagate a clinkering reaction upward through the charge to the upper surface. In a seventh specific method of operating in a fixed hearth furnace, a zone of heat is propagated clownward from the upper surface by conducting furnace gases downward through the charge. The composition and temperature of the furnace gases are so controlled, that a clinkering reaction is initiated attheupper surface and is propagated downward through the upper portion of the charge;

during the heating stage, but more; slowly than the downward progress of the heating zone. The downward current of furnace gases is discontinued and is replaced by an upward air current before the zone [of heat reaches the lower surface of the charge,-

and while a relatively'thick layerof cold 7 7 material remains adjacent to the perforated hearth. hen the gas currents are re versed, the upper portionof the charge is composed of clinkered material, the intermediate portion is composed of hot un Under these conditions, the furnace gases may be used only, to heat the upper, surface of the charge, and to maintain the working temperature of the furnace; and both the upward and the downward gas currents thereafter conducted through the charge, may be composed of air suitably modified as to composition, temperature and pressure. I do not wish to be limitedto the seven de scribed specific methods of operation, because the essential features of the process may be combined in various other ways to produce additional methods of operation.

The seven specific methods of operation have been described as theyare carried on in a fixed hearth furnace, where the two gas currents are conducted alternately through the charge, and where at a given time during the operation, the cold materialfthe heated material and the clinkered material are superposed upon each other in substantially horizontal zones or layers; but when I zontal layers found in a pot roaster or in a fixed hearth furnace. When the first specific method of operation is carried on continuously in a furnace of the chain grate stoker type, a thin layer of heated material gressively thinner.

. is near the exit end of the furnace.

is formed at the upper surface of the moving charge, near the entrance end of the furnace, by the action of the furnace gases. As the heat is being propagated downward, the charge is moving horizontally toward the exit end of the furnace. The thin layer of heated material becomes progressively thicker, as it moves horizontally from the entrance end of the furnace toward the exit end, until its thickness is the same as the depth of the charge. The cold portion of the charge which underlies the heated material, becomes progressively thinner as it moves horizontally from the entrance end of the furnace toward the exit end. The cold portion of the charge thereforehas the form of a wedge, the thick end of which is at the entrance end of the furnace; and this wedge of cold material underlies another wedge composed of heated materlal, the thin end of which is at the entrance end of the furnace. The clinkering reaction initiated at the lower surface of the charge, forms a thin layer of clinkered material at that surface; and as the charge continues to move horizontally toward the exit end of the furnace, this layer of clinkered material be comes progressively thicker, and the overlying zone of heated material becomes pro- The clinkered portion of the charge therefore has the form of a wedge, the thick end of which is at the exit end of the furnace; and it underlies a wedge of heated material, the thin end of which It is therefore evident that the moving charge in the furnace is always composed of threewedge shaped bodies of material. The thin end of the cold material wedge is adjacent to the thin end of the clinkered material wedge at the lower surface of the charge, and these wedges underlie the double wedge of heated material, which has one thin end at the entrance-end of the furnace and the other thin end near the exit end of the furnace. The bent plane that forms the dividing surface between the three bodies of material in the furnace, has one end at the top of the charge at the entrance end of the furnace, from which it inclines downward to the bottom of the charge by following the upper surface of the cold material wedge, and then it inclines upward to the top of the charge near the exit end of the furnace by following the upper surface of the clinkered material wedge. These two inclines of thebent plane usually form two straight line declivities that meet at the lower surface of the charge, but the controllable conditions of operation may be so varied that the bent plane will follow a curved path. In the second specific method of operating in a moving hearthfrrnace, a. clinkering reactionis initiated at the upper surface of the charge by the action of the downward our rent of furnace gases, and this clinkering reaction is propagated downward from the upper surface, but more slowly than the downward progress of the zone of heat. The cold portion of the charge therefore has the form of a wedge the thick endof which is at the entrance end of the furnace, and it underlies a relatively thin wedge of hot unclinkered material the thin end of which is at the entrance end of the furnace; and this wedge in turn underlies a second. thin wedge composed of clinkered material the thinend of which is also near the entrance end of the furnace. The clinker which is formed at the lower surface of the charge and which is propagated in an upward direction by the action of the upward air current, forms a wedge the thick end of which is at the exit end of the furnace, and it underlies a relatively thin wedge of hot unclinkered material the thin end of which is near the exit end of the furnace; and this wedge in turn underlies a layer of clinkered material of substantially uniform thickness. The moving charge in the furnace is therefore composed of four bodies of material, three of which are wedge shaped and one of which is wedge shaped in part. The thin end of the cold material wedge is adjacent to the thin end of the clinkered material wedge at the lower surface of the charge, and these wedges underlie the double wedge of heated material, which has one thin end at the entrance end of the furnace and the other thin end near the exit end of the furnace. The layer of clinker formed in the upper portion of the charge, is wedge shaped near the entrance end of the furnace and has the shape of a rectangular slab near the exit end of the furnace; and this composite shaped layer of clinker overlies the double wedge of heated material. In the third specific method of operating in a moving hearth furnace, the cold material forms a wedge the thick end of which is at the entrance end of the furnace, and it underlies a wedge of heated material the thin end of which is at the entrance end of the furnace. In the upper portion of the charge, the clinkered material forms a wedge the thick end of which is at the exit end of the furnace, and this wedge overlies a wedge of the heated material the thin end of which is near the exit end of the furnace. The double wedgeof heated material is substantially as long as the furnace and overlies the relatively short wedge of cold material and underlies the relatively short wedge of clinkered material. In the fourth specific method of operating in a moving hearth furnace, the clinkered material in the upper portion of the charge and which extends substantially the whole length of the furnace, forms a wedge the thin end of which is near the entrance end of the furnace and the thick end: of which is at the exit end. The heated material forms a double wedge which is also substantially as long as the furnace and which underlies the wedge of clinkered material. This double wedge of heated material rests for a part of its length, on the perforated hearth of the furnace, and for the remainder of its length, overlies the wedge of cold material the thick end of which is at the entrance end of the furnace. This wedge of cold material is much shorter than the superposed wedges of heated material and of clinkered material, and has the same position in the lower portion of the charge as in the previous examples. In the fifth specific method of operating in a moving hearth furnace, the wedge of cold material in the lower portion of the charge is substantially as long as the furnace, and has its thick end at the entrance end of the furnace and its thin end near the exit end of the furnace. The cold material wedge throughout its whole length, underlies a relatively thin layer of heated material; and this layer in turn underlies the clinkered material wedge which is substantially as long as the furnace, and which has its thin end near the entrance end of the furnace and its thick end at the exit end of the furnace. In the sixth specific method of operating in amoving hearth furnace, the moving charge is composed of three bodies of material having substantially the same form and arrangement as in the first specific method of operating, except that the clinkered material wedge is shorter and the cold material wedge is longer, because the movement of the charge carries the thin end of the cold material wedge beyond the plane of separation between the upward and the downward gas currents. In the seventh specific method of operating in a moving hearth furnace, the moving charge is composed of four bodies of material having substantially the same form and arrangement as in the second specific method of operating, except that the clinkered material wedge in the lower portion of the charge shorter and the cold material wedge is longer, because the movement of the charge carries the thin end of the cold material wedge beyond the plane of separation between the upward and the downward gas currents. It is evident that every change in the essential features of the process, produces a corresponding change in the form and arrangement of the various bodies of material that constitute the moving v charge in the furnace.

In the treatment of the materials described in these examples, various modifications will suggest themselves to those skilled in the art. It may be desirable to moisten the charge to form interstices for the uniform distribution of the gas currents through the mass.

The temperature in the zone of reaction may be regulated or the character ofthe reaction may be varied by the additio-nof steam, products of'combustion or other modifying elements, to the gas charge, may be oxidizing, neutral or reduc-' ing. lVhere the ash from the combustion of solid fuel is an undesirable ingredient of the finished product, liquid orsemi-liquid fuel may be used as the heat developing component. lVith material of a highly refractory nature, it may be desirable to add a flux to lower the clinkering temperature.

I do not wish to be limited to treatment of the specific materials described in the ex amples, nor do I wish to be limited to the specific details of treatment there described, since it will be evident to those skilled in the art that this invention applies to the treatment of any material, or any mixture of materials, of such a nature that one or more reactions can be propagated through the mass in one or more directions, by means of two currents of gas conducted through the mass in different directions. It will be further evident that the kinds of treatment 210?.

corded the material are not limited to calcining, roasting, reducing or clinkering, but may include any treatmentwhich can be carried on by the methods described. It will also be evident that the gaseous currents can be alike or different in composition, and that each current may be either an oxidizing of a reducing agent, provided that under suitable control of conditions it has the property of propagating the reactions in the manner described.

It is to be understood that the words finely divided as herein used, have reference to any degree of subdivision that best adapts the material to treatment by my process, as some materials respond to treatment better when in a relatively coarse concondition while other materials respond to treatment only when in a finely divided state. It is to be also understood that where the materials are described in th claims as containing various components, the various components may be originally con tained in the material or they may be added to the material to prepare it for treatment.

' hat I claim is:

1. The process of treating finely divided metal-bearing material. capable of undergo ing propagative reaction, which comprises initiating a reaction in a mass of the material, conducting a current of reaction-supporting gas through the. mass in one direction, conducting another current of reactionsupporting gas through the mass in another direction, and controlling conditions so as to cause propagative reaction between components of the currents of gas and of the mass.

2. The process oftreating finelydivided non-combustible material, which comprises mixing heat developing elements with the material to form a mixture capable of undergoing propagative reaction, initiating a reaction in a mass of the mixture, conducting a current of reaction-supporting gas through the mass in one direction, conducting another current of reaction-supporting gas through the mass in another direction, and controlling conditions so as to cause propagative reaction between components of the currents of gas and of the mass.

3. The process of treating finely divided metal bearing material containing heat de veloping components, which comprises initiating a reaction in a mass of the material,

conducting a current of reaction-supporting gas through the mass in one direction, conducting another current of reaction-supporting gas through the mass in another direction, and controlling conditions so as to cause components of the mass to react with components of the gas currents.

4. The process of treating finely divided metal bearing material containing gas form'- ing components, which comprises initiating a reaction ina mass of the material, conducting a current of reaction-supporting gas through the massin one direction, conducting another current of reaction-supporting gas through the mass in another direction, and controlling conditions so as tocause components'ot the mass to reactwith components of the gas currents.

5. The process of treating finely divided metal-bearing material capable of undergo ing propagative reaction, which comprises conducting a current of gas through a mass or" the material in one direction, conducting. another current of gasthrough the mass in 1 another direction, heatingthema'ss and con- V trolling conditions so as to propagate a reaction effect through themass.

6. The process oftreating finely divided non combust-ible material, which comprises mixing heat developing elements with the material, conducting a current of gas throughv a mass of the mixture in one direction, con ducting another current of gas through the mass in another direction, heating the mass and controllingconditions so asto propagate a reaction efiect through the mass.

7. The process of treating finely divided material containing heat developing components, which comprises conducting a current of gas through a mass of the material in one direction, conducting another current of gas through the mass in another direction, heating the mass and controlling conditions so as to propagate a reaction effect through the mass. 7

8. The process oftreating finely divided material containing v gas forming components, which comprises conducting a current of gas through a mass of the material in one direction, conducting another current of gas through the mass in another direction, heating the mass and controlling conditions so as to propagate a reaction efiect through the mass.

9. The process of treating finely divided metal-bearing material capable of being clinkered, which comprises conducting a current of gasthrough a mass of the material in one direction, conducting another current of gas through the mass in another direction, heating the mass and controlling conditions so as to clinker the mass.

10. The process of treating finely divided non-combustible material, which comprises mixing combustible elements with the material, conducting a current of gas through a mass of the mixture in one direction, conducting another current of gas through the mass in another direction, heating the mass and controlling conditions so as to clinker the mass.

11. The process of treating finely divided metal-bearing material containing combustible components, which comprises conducting a current of gas through amass of the material in one direction, conducting another current of gas through the mass in another direction, heating the massLand causing the mass to clinker.

12. The process of treating finely divided metal-bearing material containing carbonaceous components, which comprises conducting a current of gas through a mass of the material in one direction, conducting another current of gas through the mass in another direction, heating the mass and causing the mass to clinker. V

13. The process of treating finely divide metal-bearing material containing combustion-supporting and other components,

which comprises conducting a current of gas through a mass of the material in one direction, conducting a gas which is reactive With some of the components of the material through the mass in another direction,

heating the mass and causing the mass to agglomerate.

14C. The process of treating finely divided metal-bearing material capable of being clinkered, which comprises conducting a current of gas downward through a mass of the material, conducting another current of gas upward through the mass, heating the mass and controlling conditions so as to clinker the mass.

'15. The process of treating finely divided non-combustible material, which comprises mixing combustible elements with the material, conducting a current of gas downward'through a mass of the mixture, conducting another current of gas upward through the mass, heating the mass and controlling conditions so as to clinker the mass.

. a mass of the material, conducting another current of gas upward through the mass, heating the mass and causing the mass to clinker;

18. The process of treating finely divided metal-bearing material containing combustion-supporting and other components, which comprises conducting a current of gas downward through a mass of the material, conducting a gas which is reactive with some of the components of the mate rial :upward through the mass, heating the mass and causing the mass toagglomerate.

19. The process of treating finely divided metal-bearing material capable of being clinkered, whichcomprises forming a mass of the material on a movable perforated furnace-hearth, conducting a current of gas in one direction through the mass, conducting another current of gas in another direction through the mass, moving the mass and heating the mass and controlling the movement of the mass and the thermal and other conditions so as to clinker the mass.

20. The process of treating finely divided non-combustible material, which comprises mixing combustible elements with the material, forming a mass of the mixture on a movable perforated furnace-hearth, conducting a current of gasin one direction through the mass, conducting another current of gas in another direction through the mass, mov-' ing the mass and heating the mass, and controlling the movement of the mass and the thermal and other conditions so as to clinker the mass.

21. The process of treating finely divided metal-bearing material containing combustible components, which comprises. forming a mass of the material on a movable perforated furnace-hearth, conducting a current of gas in one direction through the mass, conducting another current of gas in another direction through the mass, moving the mass and heating the mass, and controlling the movement of the mass and the thermal and other conditions thereby causing the mass to of gas in one direction through the mass,

conducting another current of gas in another direction through the mass, moving the mass and heating the mass, and controlling themovement of thelmass and the thermal and other conditions thereby causing the mass to clinker.

23. The process of treating finely divided" metal-bearing material containing combus tion-su-pporting and other 'components,which comprises forming a mass ofthe material on a movable perforated furnace-hearth, con; ducting a current of gasin one direction through the mass, conducting-a gas'whic-h is reactive with some ofthe' components of the material in another direction through the mass, moving the mass and'heating the mass, and controlling the movement of the mass and the thermal and" other conditions thereby causing the mass toagglomerate. 24-; The process of treating finely divided metal-bearin material capable of being clinkered, whlch comprises forming a mass of the material One. movable perforated furnace-hearth, vconductiirga current of gas downward through the mass; conducting another current of gas upward through the mass-and during the operation moving the mass, heating the mass; and controlling the movement of the mass and the thermal and other conditions so as to clinkert'he mass. 1 25. The process of treating finely divided non-combustible material, which comprises mixing combustible elementswiththe material, forming a mass of the mixture-on a. movable perforated furnace-hearth, conducting a currentof gas downward through the metal-bearing material containing combustible components, whichjcomprises forming a mass of the material on a movable perforated furnace-hearth, heating the upper surface of the mass, conducting a current of gas downward through the mass, conducting another current of gas upwardthrough the mass, and during theoperation moving the mass, heat-ing the mass, and controlling the movement of the mass and the thermal and other conditions so as to cause the mass to clinker. V 27. The process of treating finely divided metal-bearing material containing carbona ceous components, which comprises forming a mass of the material on a movable perfoe rated furnace-hearth, heating the upper surfaceof themass, conducting acurrentof gas 7 mass, heating the mass, and controlling the movement of. the mass and the thermal and other conditions so asjtocause the mass to clinker. V 28. The process of treating finely divided metal-bearing material containing combustion-supporting and other components, which comprises forming a mass ofthe material on a movable perforated.furnace hearth, heatingthe upper surface of the mass, conducting a current of gas downwardthrough the mass, conducting a gas which is reactive With some of the components of the material upward through the mass, and during the operation moving the mass, heating the mass,

and controlling the movement of the mass and the thermal and other conditions so as to cause the mass to agglomerate. V

r 29. The process of treating a finely divided oxid ore mixture containing combustible components, which comprises forming a mass of the mixture on a movable perforated furnace-hearth, transmitting heat from a body of hot gases to the upper surface of the mass, conducting a current of gas downward through the mass, conducting another current of gas upward through the mass, and during the operation moving the mass, heat ing the mass, and controlling the movement of the mass and the thermaland other conditions so as to cause the mass to clinker.

30. The process of treating a'finely .divided oxid ore mixture containingcarbonaceous components, which comprises forming 5 a mass of the mixture on a movable perfo-.

rated furnace-hearth, transmitting heat from a body of hot gases to the upper surface of the mass, conducting a current of gas downward through the mass,conducting another 40 current of gas upward through the mass, and

during the operation moving the mass, heating the mass, and controlling the movement of the mass and the thermal and other conditions so as to cause the mass to clinker.

31. The process of continuously treating finely divided metal-bearing material capable of being clinkered, which comprises continuously feeding the material to the moving perforated hearth of a reverberatory furnace to form a moving mass of the material, continuously conducting a current of gas downward through the moving mass in one part of the furnace, continuously conducting another current of gas upward through the moving mass in another part of the furnace, continuously heating the moving mass and controlling conditions so as to continuously clinker the mass.

32. The process of continuously treating finely divided non-combustible material capable of being clinkered, which comprises mixing combustible elements with the material, continuously feeding the mixture to the moving perforated hearth of a reverberatory furnace to form a moving mass of the mixture, continuously conducting a current of gas downward through the moving mass in one part of the furnace, continuously conducting another current of gas upward through the moving mass in another part of the furnace, continuously heating the moving mass and controlling conditions so as to continuously clinker the moving mass. 7

33. The process of continuously treating finely divided metal-bearing material containing combustible components, which comprises continuously feeding the material to the moving perforated hearth of a reverberatory furnace to form a moving mass of the material, continuously heating the upper surface of the moving mass, continuously conducting a current of gas downward through the moving mass in one part of the furnace, continuously conducting another current of gas upward through the moving mass in another part of the furnace, continuously propagating heat through the moving mass and causing the moving mass to clinker continuously.

34:. The process of continuously treating finely divided metal-bearing material containing carbonaceous components, which comprises continuously feeding the material to the moving perforated hearth of a reverberatoryfurnace to form a moving mass of the material, continuously heating the upper surface of the moving mass, continuously conducting a current of gas downward through the moving mass in one part of the furnace, continuously conducting another current of gas upward through the moving mass in another part of the furnace, continuously propagating heat through the moving mass and causing the moving mass to clinker continuously. V

, 35. The process of continuously treating finely divided metal-bearing material containing combustion-supporting and other components, which comprises continuously 11o feeding the material to the moving perforated hearth of a reverberatory furnace to form a moving mass of the material, con-' tinuously heating theupper surface of the moving mass, continuously conducting a current of gas downward through the moving mass in one part of the furnace, continuously conducting a gas which is reactive with some of the components of the material upward through the moving mass in another part of the furnace, continuously propagating heat through the moving mass and causing the moving mass to agglomerate continuously.

36. The process of continuously treating a finely divided oxid ore mixture containing combustible components, which comprises continuously feeding the mixture to the moving perforated hearth of a reverbera tory furnace to form a moving mass of the mixture, continuously transmitting heat from a body of hot gases to the upper surface of the moving mass, continuously conducting a current of gas downward through and causingt-he moving mass to clinker con-- tinuously. V

37. The processof continuously treating a .finely divided oxid ore mixture containing carbonaceous components, which comprises continuously feeding the mixture to the moving perforated hearth of a reverberatory furnace to form a moving mass ofthe miX- Goples 0t this patent may be obtained for five cents each, by addressing the Commissioner vo f Patients,

V ,Washingtom'LG." I v moving mass, continuously conducting a ing mass in one part of thefurnacefcontinuously 'conductinganother current of gas upward through the moving mass in another partof the furnace, continuously propagating heat. through'the moving'mass and 'caus-v ingthe moving mass to 'clinkericontinuously;

In testimony'whereof Ihave hereunto set my hand this 6th day ofziApril, I910, in they presence of-two Witnesses. u

'. 'FREDERICK W. YOST.

lVitnesses: i I I v SAMUEL "W. MOMUNN,

EDWARD A. BnRr I.