CN109368665B - Method and system for recycling and treating direct flotation tail salt - Google Patents
Method and system for recycling and treating direct flotation tail salt Download PDFInfo
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Abstract
The invention provides a direct flotation tail salt recovery processing method and a system, wherein the direct flotation tail salt is slurry comprising sodium chloride and carnallite particles, and the method comprises the following steps: thickening step S1: sending the tail salt slurry to a thickener for thickening so as to improve the concentration of the tail salt slurry; washing step S2: sending the concentrated tail salt slurry to a washing tank, adding fresh water into the washing tank, and washing under the stirring action to dissolve carnallite particles in the tail salt slurry; solid-liquid separation step S4: and carrying out solid-liquid separation on the washed tail salt slurry by adopting a solid-liquid separation device to obtain a solid phase containing sodium chloride and a potassium-containing filtrate. According to the technical scheme, sodium chloride in the direct flotation tail salt can be classified according to market demands.
Description
Technical Field
The invention relates to the field of resource recycling, in particular to the technical field of recovery treatment of direct flotation tail salt.
Background
As the storage amount of the potash fertilizer in China only accounts for about 1.6 percent of the world, the domestic requirements cannot be met. Therefore, in order to develop national industry and develop domestic resources, the production scale of potash fertilizers is continuously enlarged. A large amount of tail salt is discharged every year, the potassium content of the tail salt is low and is generally less than 2%, and the tail salt cannot be well reused for production at present. In recent years, along with the annual increase of the exploitation amount of potassium salt in a firewood basin, the dilution speed of potassium salt resources is increased, and how to improve the recycling of the potassium resources is a problem which must be faced by the production of potassium fertilizers. Therefore, the positive flotation tail salt is developed and reused, so that waste materials can be changed into valuable materials, and the resource and environmental pressure can be effectively relieved.
The potassium chloride fertilizer is produced by using soluble sylvite ore carnallite and sylvite as main material and through a floatation process. The principle of the flotation method is that the mineral particles are gathered at the liquid-gas interface through the hydrophobic characteristic of the surfaces of the mineral particles or the hydrophobic characteristic obtained after the action of a flotation agent is added. The normal flotation method is that the pulp of raw ore after hydrolysis is mixed with chemical agent in a flotation tank, and then stirred and aerated to make potassium chloride particles float upwards and scraped out along with the foam, and then dehalogenation and washing are carried out to obtain potassium chloride product, and sodium chloride is left in the tail salt slurry and discharged.
The direct flotation tail salt is sodium chloride slurry discharged in the direct flotation production process, wherein a small amount of carnallite particles are generally entrained, and the tail salt is required to contain KCl less than 2.0 percent according to the control index of the direct flotation process. Sometimes the KCl content reaches around 4% due to problems such as raw ore particle size, process control, etc.
At present, each potash fertilizer production unit does not have an effective tail salt treatment mode, and the open air stacking treatment is generally adopted. For a long time, the stacking site of the tail salt is larger and larger. As the potassium chloride contained in the tail salt cannot be effectively utilized, and the sodium chloride cannot be directly used for other industrial production, the waste of resources is undoubted.
Disclosure of Invention
The invention aims to provide a method and a system for recycling and treating direct flotation tail salt, aiming at the problem that the direct flotation tail salt in the prior art cannot be effectively utilized.
According to a first aspect of the present invention, there is provided a direct flotation tail salt recovery processing method, wherein the direct flotation tail salt is a slurry containing sodium chloride and carnallite particles, the method comprises the following steps, a thickening step S1: sending the tail salt slurry to a thickener for thickening so as to improve the concentration of the tail salt slurry; washing step S2: sending the concentrated tail salt slurry to a washing tank, adding fresh water into the washing tank, and washing under the stirring action to dissolve carnallite particles in the tail salt slurry; solid-liquid separation step S4: and carrying out solid-liquid separation on the washed tail salt slurry by adopting a solid-liquid separation device to obtain a solid phase containing sodium chloride and a potassium-containing filtrate.
Optionally, the method further comprises a screening step S3: screening the washed tail salt slurry by adopting screening equipment, and grading the solid phase obtained by screening by different particle sizes to produce sodium chloride solids of different grades; and (4) performing solid-liquid separation on the screened tail salt slurry in a step S4.
Optionally, the thickening step S1 further includes increasing the solid phase volume concentration of the tail salt slurry to 45% to 55% after the thickening treatment by the thickener.
Optionally, the step S1 of thickening further comprises returning the supernatant produced in the thickener to the salt pan for producing carnallite again.
Optionally, the washing step S2 further comprises adding fresh water according to KCl-NaCl-MgCl based on the content of potassium chloride2-H2And (4) calculating the water quantity of the dissolved potassium chloride by using an O quaternary water-salt system phase diagram.
Optionally, the screening step S3 further includes adding a fresh water rinse during the screening process of the screening device to reduce the mother liquor entrained in the solid phase.
Optionally, the screening step S3 further includes that the screening device includes one of a vibrating screen, a rotating screen, and a fixed screen.
Optionally, the screening step S3 further includes dewatering the different grades of sodium chloride solids by heap filtration to obtain dried sodium chloride solids for use by the soda industry.
Optionally, the solid-liquid separation step S4 further includes that the solid-liquid separation device includes one of a centrifuge, a plate and frame filter, a bag filter and a belt filter.
Optionally, the solid-liquid separation step S4 further includes: and adding fresh water for leaching in the solid-liquid separation process of the solid-liquid separation device to reduce the mother liquor carried in the solid phase.
Optionally, the solid-liquid separation step S4 further includes: and returning the potassium-containing filtrate to the salt pan to produce the carnallite again.
According to a second aspect of the present invention, there is provided a direct flotation tail salt recovery processing system, wherein the direct flotation tail salt is a slurry comprising sodium chloride and carnallite particles, the system comprising a thickener for receiving a tail salt slurry and thickening the slurry to increase the concentration of the tail salt slurry; the washing tank is connected behind the thickener, receives the thickened tail salt slurry, adds fresh water and washes the tail salt slurry under the stirring action so as to dissolve carnallite particles in the tail salt slurry; and the solid-liquid separation device is connected behind the washing tank, receives the washed tail salt slurry and performs solid-liquid separation to obtain a solid phase containing sodium chloride and a potassium-containing filtrate.
Optionally, the system further comprises a screening device connected between the washing tank and the solid-liquid separation device, and configured to receive and screen the washed tail salt slurry, and perform classification of different particle sizes on a solid phase obtained through screening to produce sodium chloride solids of different grades; and feeding the screened tail salt slurry into the solid-liquid separation device.
Optionally, after the thickener performs thickening treatment on the tail salt slurry, the solid phase volume concentration of the tail salt slurry is increased to 45% -55%.
Optionally, the supernatant liquor produced in the thickener is returned to the salt pan for the production of carnallite again.
Optionally, the amount of fresh water added to the washing tank is based on the content of potassium chloride and is based on KCl-NaCl-MgCl2-H2And (4) calculating the water quantity of the dissolved potassium chloride by using an O quaternary water-salt system phase diagram.
Optionally, a fresh water rinse is added to the screening process of the screening device to reduce the mother liquor entrained in the solid phase.
Optionally, the screening device comprises one of a vibrating screen, a rotating screen, a stationary screen.
Optionally, the different grades of sodium chloride solids are dewatered by means of heap filtration to obtain dried sodium chloride solids for use by the industrial soda industry.
Optionally, the solid-liquid separation device comprises one of a centrifuge, a plate and frame filter, a bag filter, and a belt filter.
Optionally, a fresh water rinse is added in the solid-liquid separation process of the solid-liquid separation device to reduce the mother liquor entrained in the solid phase.
Optionally, the potassium-containing filtrate is returned to the salt pan for the production of carnallite again.
The technical scheme of the invention has the advantages that:
1) according to the technical scheme of the invention, potassium chloride in the direct flotation tail salt can be recycled, and sodium chloride can be classified according to market condition requirements, so that the waste of resources is avoided, and the utilization rate of the direct flotation tail salt resources is greatly improved;
2) the technical scheme of the invention has simple process flow and can produce sodium chloride products with different grain size grades.
Drawings
Figure 1 shows a flow diagram of a positive flotation tail salt recovery treatment method according to the invention.
Figure 2 shows a flow diagram of another positive flotation tail salt recovery treatment process according to the invention.
Figure 3 shows a schematic diagram of one embodiment of a positive flotation tail salt recovery processing system according to the present invention.
Figure 4 shows a schematic diagram of another embodiment of a positive flotation tail salt recovery processing system according to the present invention.
Detailed Description
In the following detailed description of the preferred embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, specific features of the invention, such that the advantages and features of the invention may be more readily understood and appreciated. The following description is an embodiment of the claimed invention, and other embodiments related to the claims not specifically described also fall within the scope of the claims.
Figure 1 shows a flow diagram of a positive flotation tail salt recovery treatment method according to the invention.
As shown in fig. 1, a direct flotation tail salt recovery processing method is provided, wherein the direct flotation tail salt is slurry containing sodium chloride and carnallite particles, and the method comprises the following steps of thickening step S1: sending the tail salt slurry to a thickener for thickening so as to improve the concentration of the tail salt slurry; washing step S2: sending the concentrated tail salt slurry to a washing tank, adding fresh water into the washing tank, and washing under the stirring action to dissolve carnallite particles in the tail salt slurry; solid-liquid separation step S4: and carrying out solid-liquid separation on the washed tail salt slurry by adopting a solid-liquid separation device to obtain a solid phase containing sodium chloride and a potassium-containing filtrate.
In the direct flotation production process, potassium chloride particles are scraped out of the direct flotation tank along with the upward flotation of the foam, and discharged slurry is tail salt containing sodium chloride, namely the direct flotation tail salt. The direct flotation tail salt slurry may also have a small amount of carnallite particles entrained therein, and possibly a larger amount of silt, due to problems with the raw ore particle size and the control of the direct flotation process. The main components of the carnallite particle are potassium chloride and a small amount of magnesium chloride, and the carnallite particle is easy to dissolve in water. The technical scheme of the invention aims to separate sodium chloride and carnallite particles in the direct flotation tail salt to obtain sodium chloride solid phase and potassium-containing liquid phase with different grades and higher purity.
Because the direct flotation tail salt exists in the form of slurry, the direct flotation tail salt can be directly sent to a thickener for thickening without other treatment. Because the positive flotation reject slurry has a low solids content, it needs to be concentrated initially. The thickener is a solid-liquid separation device based on gravity settling effect, and is generally a cylindrical shallow groove with a conical bottom, which is built by taking concrete, wood or a metal welding plate as a structural material. Generally, the ore pulp with the solid content of 10-20 percent can be concentrated into underflow ore pulp with certain concentration through gravity settling, and the thickened underflow ore pulp is discharged from a underflow opening at the bottom of the thickener under the action of a rake which is arranged in the thickener and runs at a slow speed. The cleaner clear liquid generated at the upper part of the thickener is discharged from an annular chute at the top.
And (3) the concentrated direct flotation tail salt slurry enters a washing tank, and because carnallite particles are easy to dissolve in water, fresh water is added into the washing tank to completely dissolve the carnallite particles in the direct flotation tail salt slurry. The purpose of this step is to remove impurities, dissolve a small amount of carnallite particles entrained in the solid phase into the liquid phase, and increase the content of sodium chloride in the solid phase. The amount of fresh water added into the washing tank needs to be controlled properly, because the production period of returning the potassium-containing liquid phase to the salt field is influenced by too much water, and the grade of the solid-phase sodium chloride product is influenced by too little water.
And carrying out solid-liquid separation on the washed direct flotation tail salt slurry through a solid-liquid separation device, thereby achieving the purpose of dehydrating the solid phase containing sodium chloride. When the silt content of the raw ore is low, the positive flotation tail salt slurry can directly obtain a sodium chloride solid phase with high purity and a potassium-containing filtrate after solid-liquid separation; when the silt content of the raw ore is high, a large amount of silt may be contained in a solid phase containing sodium chloride obtained after the direct flotation tail salt slurry is subjected to solid-liquid separation, and the purity of the sodium chloride is affected.
Optionally, the thickening step S1 further includes increasing the solid phase volume concentration of the tail salt slurry to 45% to 55% after the thickening treatment by the thickener.
The thickener can concentrate the positive flotation tail salt slurry with lower solid content into 45-55% underflow slurry through the gravity settling effect, and the underflow slurry can flow out of the underflow opening at the bottom of the thickener and then enter the washing tank.
Optionally, the step S1 of thickening further comprises returning the supernatant produced in the thickener to the salt pan for producing carnallite again.
The supernatant liquor produced by the thickener is discharged from an annular chute at the top of the thickener and returns to the salt pan, and the carnallite ore is produced again after the magnesium-potassium ratio is adjusted. Thus, the waste of resources and the pollution to the environment can be avoided.
Optionally, the washing step S2 further comprises adding fresh water according to KCl-NaCl-MgCl based on the content of potassium chloride2-H2And (4) calculating the water quantity of the dissolved potassium chloride by using an O quaternary water-salt system phase diagram.
Fresh water is added into the washing tank to dissolve and wash a small amount of carnallite in the positive flotation tail salt slurry, the magnesium chloride in the carnallite has low content and high solubility, and the carnallite can be dissolved along with potassium chloride generally. The amount of the fresh water added may be determined by the solid phase component in the slurry of the direct flotation tail salt, for example, KCl-NaCl-MgCl is used based on the content of potassium chloride2-H2And calculating the water quantity of the dissolved potassium chloride by using an O quaternary water salt system phase diagram. For example, the amount of fresh water for dissolving potassium chloride and magnesium chloride is calculated to be different according to the solid phase component or the content of each component of different slurries. Or according to an empirical formula, wherein the empirical formula can be, for example, a formula summarized by stabilizing the composition of the slurry produced under the same process conditions summarized in the production process within a certain range and summarizing the washing effect which can be achieved by adding water according to experience. By combining the method, the addition amount of fresh water added into the washing tank in the technical scheme of the invention can be 1/15-1/10 of the volume of the concentrated direct flotation tail salt slurry.
Optionally, the solid-liquid separation step S4 further includes that the solid-liquid separation device includes one of a centrifuge, a plate and frame filter, a bag filter and a belt filter.
Centrifuges are machines that utilize centrifugal force to separate components of a mixture of liquid and solid particles or liquid and liquid. The centrifuge is mainly used for separating solid particles from liquid in suspension, or separating two liquids which have different densities and are insoluble with each other in emulsion, and can also be used for draining the liquid in wet solid, so that the effect of dewatering is achieved, for example, clothes are dried and wetted by a washing machine. Some settling centrifuges can also grade solid particles according to density or granularity by utilizing the characteristic that solid particles with different densities or granularities have different settling speeds in liquid.
The plate frame filter is the first machine used in chemical dewatering. Although the plate-and-frame filter is generally operated intermittently, the capital equipment investment is large, and the filtering capacity is low, the plate-and-frame filter has the advantages of large filtering driving force, high solid content of filter cakes, clear filtrate, high solid recovery rate, low conditioning medicine consumption and the like, and is widely applied to some fields.
The bag filter is a multipurpose filtering device which has the advantages of novel structure, small volume, simple and flexible operation, energy conservation, high efficiency, closed work and strong applicability. Bag filters are a new type of filtration system. The bag filter is internally provided with a metal mesh basket for supporting a filter bag, liquid flows in from an inlet, flows out from an outlet after being filtered by the filter bag, impurities are intercepted in the filter bag, and the filter bag can be continuously used after being replaced.
The belt filter is also called a chain belt filter, is one kind of continuous filter and is a new type of high-efficiency dewatering equipment. The operation condition is similar to a belt conveyor, slurry is dehydrated, solid and liquid are separated, and dregs are filtered in the conveying process. There are two types of structural forms: pressurized and depressurized. The former is more common, and the pressure-dividing filter and the squeezer are two types; the latter is a vacuum filter. The belt filter can be formed into a plurality of different machine types due to different arrangements and combinations of the press rolls. The plate-and-frame filter press has the advantages of simple structure, high dewatering efficiency, large treatment capacity, low energy consumption, low noise, high automation degree, continuous operation, easy maintenance and the like, and the cost and the operating cost of the plate-and-frame filter press are reduced by more than 30 percent compared with those of a plate-and-frame filter press.
Because the sodium chloride in the direct flotation tail salt has larger grain size and possibly larger silt content, a centrifugal machine can be adopted for centrifugal dehydration. Preferably, a belt filter or a centrifuge can be used for carrying out solid-liquid separation and dehydration on the screened positive flotation tail salt slurry, and the best effect is achieved.
Optionally, the solid-liquid separation step S4 further includes: fresh water leaching can be added in the solid-liquid separation process of the solid-liquid separation device to reduce the mother liquor carried in the solid phase.
At the middle section of the solid-liquid separation process of the solid-liquid separation device, most of water in the solid phase is removed, and at the moment, a fresh water leaching process can be added to leach potassium chloride and magnesium chloride contained in mother liquor carried in the solid phase, so that the purity of sodium chloride in the solid phase is further improved, and the recovery rate of potassium in filtrate is improved. Meanwhile, the fresh water leaching is arranged in the middle section, so that the dehydration can be continued after the solid phase leaching, and the dehydration is basically finished when the solid phase leaching leaves the solid-liquid separation device, thereby meeting the industrial requirements. For example, in the actual operation process, the belt length can reach 20-30 m, most of water is removed when the separated solid phase runs from one end to the middle section of the belt filter cloth, a fresh water leaching is added, the machine still runs for a period of time after the purity of sodium chloride in the solid phase and the potassium content in the filtrate are further improved, and the solid phase still continues to be dehydrated for a period of time, so that the dehydration can be completed when the solid phase runs to the other end of the belt filter cloth. The operation can achieve the purposes of solid-liquid separation and dehydration, can further improve the purity of sodium chloride in a solid phase and the recovery rate of potassium in filtrate, and is simple and practical and good in effect. The same principle is also explained by taking a centrifugal machine as an example, for example, the centrifugal machine finishes the solid-liquid separation of the positive flotation tail salt slurry, discharges supernatant liquid, carries out fresh water rinsing on the remained sediment, and continues the centrifugal separation after rinsing to remove residual water to obtain a solid phase containing sodium chloride.
Optionally, the solid-liquid separation step S4 further includes: and returning the potassium-containing filtrate to the salt pan to produce the carnallite again.
And returning the potassium-containing filtrate to a salt pan, adjusting the magnesium-potassium ratio, and then producing the carnallite again, so that the waste of resources and the environmental pollution can be avoided.
Figure 2 shows a flow diagram of another positive flotation tail salt recovery treatment process according to the invention.
As shown in fig. 2, according to an embodiment of the present invention, the positive flotation tail salt recovery processing method further includes a screening step S3: screening the washed tail salt slurry by adopting screening equipment, and grading the solid phase obtained by screening by different particle sizes to produce sodium chloride solids of different grades; and (4) performing solid-liquid separation on the screened tail salt slurry in a step S4.
When the silt content of the raw ore is large, the washed direct flotation tail salt slurry may contain a large amount of silt, so that the positive flotation tail salt slurry needs to be subjected to the screening step S3. The process of dividing the material to be crushed into different size fractions by one or more layers of screening surface is called screening. The screening equipment is mechanical equipment used for separating various raw materials and various primary products into a plurality of grades according to the granularity of the materials by utilizing the actions of rotation, vibration, reciprocation, shaking and the like, or removing moisture, impurities and the like in the raw materials and the primary products, and then carrying out next processing and improving the product quality. For example, screening machines are screening devices that use the relative motion of a particulate material and a screening surface to cause a portion of the particles to pass through a screen opening and separate the material into different grades based on particle size. The screening process of the screening machine is generally continuous, and after the screened raw materials are fed to the screening machine, the materials smaller than the size of the screen holes penetrate the screen holes and are called undersize products; material larger than the mesh size is continuously discharged from the screening surface and is referred to as oversize product. And screening the washed tail salt slurry by using screening equipment to fulfill the aims of dehydration and classification, so that a target sodium chloride product is obtained. Sodium chloride particles with the particle size larger than the size of the sieve pores on the sieve surface are discharged to be oversize products, and sodium chloride particles, silt and potassium-containing filtrate with the residual particle size smaller than the size of the sieve pores on the sieve surface penetrate through the sieve pores to be undersize products and flow out from the bottom of the screening equipment. The oversize product obtained by screening is a sodium chloride solid product with higher purity.
After the treatment of the screening step, the solid-phase sodium chloride obtained by screening and grading basically meets the production requirements of industrial sodium carbonate and can be supplied to the sodium carbonate industry for use. The screening frequency can be determined according to the requirements of sodium chloride product phase, and several layers of screen surfaces are arranged when the screening is required. The screen surfaces with different screen hole sizes can be arranged by needing sodium chloride products with different grain sizes. For example, two layers of screen surfaces are arranged, which are respectively screen surfaces with two screen hole sizes, so that sodium chloride products with two particle size grades can be screened out, and the sodium chloride products can be called as a primary sodium chloride material and a secondary sodium chloride material, so as to meet different industrial production requirements, such as the production of different grades of soda ash.
The undersize product obtained after screening, namely the screened direct flotation tail salt slurry can be subjected to solid-liquid separation and dehydration through a solid-liquid separation device to obtain a solid phase containing sodium chloride and a potassium-containing filtrate. When the silt content in the carnallite raw ore is large, the silt content in the direct flotation tail salt is large, the silt is fine, and the silt flows out through the sieve holes and enters slurry, so that although the particle size of sodium chloride in the solid phase containing sodium chloride obtained after solid-liquid separation is fine, a large amount of silt still exists possibly, and the requirement of industrial soda production raw materials cannot be met, therefore, the solid phase containing sodium chloride obtained by solid-liquid separation through the solid-liquid separation device can be used in other required conditions, or further purified through silt removal treatment, or treated as waste, and the like. When the silt content in the carnallite raw ore is less, the silt content in the obtained solid phase containing the sodium chloride is less, and the solid phase containing the sodium chloride obtained by solid-liquid separation can also meet the production requirement of the industrial sodium carbonate.
Optionally, the screening step S3 further includes adding a fresh water rinse during the screening process of the screening device to reduce the mother liquor entrained in the solid phase.
In the screening and grading process, a fresh water leaching process is added to the solid phase, so that potassium chloride and magnesium chloride contained in the mother liquor carried in the solid phase can be leached, and the purity of the solid phase sodium chloride is improved again, so that the purity of the solid phase sodium chloride can meet the raw material requirement of industrial sodium carbonate production. The solid phase sodium chloride can meet the requirement of industrial sodium chloride production on raw material sodium chloride through the treatment of the step, and can be used in the sodium carbonate industry.
The purity and the water content of the sodium chloride solid products with different grades obtained according to the technical scheme of the invention can meet the production requirements of industrial soda ash, and can be directly used in the soda ash industry, such as the production processes of the soda ash, such as the Lumbran method, the Soxhlet soda process, the Hough soda process and the like.
Optionally, the screening step S3 further includes that the screening device includes one of a vibrating screen, a rotating screen, and a fixed screen.
Depending on the structural and kinematic characteristics of the screening apparatus, several types may be included, such as vibrating screens, rotating screens, stationary screens, etc.
The vibrating screen is an elastic vibrating system whose amplitude can be varied by the influence of the feed rate and other dynamic factors. The vibrating screen has the characteristics of high frequency, small amplitude, positive and negative inclination of the screen surface and the screening rate, the larger the inclination of the screen surface, the higher the flow speed, and the jumping motion of the materials on the screen surface, so that the productivity and the screening efficiency are both higher. The vibrating screen may in turn comprise: linear vibrating screens, horizontal vibrating screens, shaking screens, eccentric screens, rotary vibrating screens, circular vibrating screens, banana vibrating screens, probability screens and the like.
The rotary screen is mostly formed by folding a plate screen into a polygonal or circular cylinder, and has simple structure and long service life. The working part of the rotary screen is a cylindrical or conical screen cylinder, a rotating shaft is arranged along the symmetrical axis of the screen cylinder, the whole screen rotates around the axis of the cylinder body, and the axis is arranged at a small inclination angle under the general condition. Circular conical surface sieve section of thick bamboo horizontal installation, the material is given from the tip of drum to being taken along with the rotation of a sieve section of thick bamboo, when reaching a take the altitude, because of receiving the action of gravity to fall down by oneself, fine-grade material passes through from cylindric working surface's sieve mesh, and the coarse grain material is discharged from the other end of drum, so constantly the motion of rising and falling realizes the screening of material. The drum screen has low rotation speed, stable operation and good power balance. But the sieve mesh is easy to block and deform, the sieving efficiency is low, the working area is small, the production rate is low, and the sieve can be used for sieving and dehydrating coarse and medium-sized materials.
The fixed screen is the simplest and oldest screening machine, and the screening surface is formed by a number of parallel arranged screen bars, arranged in the same or perpendicular direction to the material flow on the screen. The screen surface is horizontally arranged (when dewatering) or obliquely arranged, the screen surface is fixed when in work, and materials slide down along the screen surface by dead weight to be screened. The fixed screen is divided into two types, namely a fixed screen grid and a strip screen. The arc screen and the cyclone screen belong to a novel fixed screen. The sieve surface of the arc sieve is arc-shaped along the material flow direction on the sieve, and the sieve bars are vertical to the material flow direction on the sieve; the screen surface of the cyclone screen is conical, and the screen bars are approximately parallel to the generatrix. They can be used for primary dewatering and desliming of slurry, and when it is worked, it can utilize centrifugal force produced when the slurry is moved along the screen surface to intensify screening. The fixed screen has simple structure, long service life, no power consumption, no moving parts and low equipment cost and use cost. Thus, although the productivity and screening efficiency are low, they are still widely used.
Optionally, the screening step S3 further includes dewatering the different grades of sodium chloride solids by heap filtration to obtain dried sodium chloride solids for use by the soda industry.
Since most of the water in the sodium chloride solid obtained by screening and classification is removed, the residual small amount of water can be further removed by a pile filtration mode.
According to the technical scheme, potassium chloride in the direct flotation tail salt is transferred into a liquid phase for recycling through a dissolving and washing process, and meanwhile, a qualified sodium chloride product required by the chemical industry is obtained.
According to the technical scheme of the invention, the full utilization of the normal flotation tail salt is realized, the generated liquid phase can be returned to the salt pan to produce the carnallite again, and the generated solid-phase sodium chloride can be classified according to market condition requirements, so that the comprehensive utilization of resources is realized.
Figure 3 shows a schematic diagram of one embodiment of a positive flotation tail salt recovery processing system according to the present invention.
As shown in fig. 3, a direct flotation tail salt recovery processing system is provided, wherein the direct flotation tail salt is slurry containing sodium chloride and carnallite particles, and the system comprises a thickener M1 for receiving tail salt slurry and thickening the slurry to increase the concentration of the tail salt slurry; a washing tank M2 connected to the rear of the thickener M1, receiving the thickened tail salt slurry, adding fresh water and washing the tail salt slurry under the action of stirring to dissolve carnallite particles in the tail salt slurry; and a solid-liquid separator M4 connected to the washing tank M2, and receiving the washed tail salt slurry and performing solid-liquid separation to obtain a solid phase containing sodium chloride and a potassium-containing filtrate.
Figure 4 shows a schematic diagram of another embodiment of a positive flotation tail salt recovery processing system according to the present invention.
As shown in fig. 4, the system according to the present invention may further include a screening device M3 connected between the washing tank M2 and the solid-liquid separation device M4 for receiving the washed tail salt slurry and screening, and classifying the screened solid phase into different particle sizes to produce different grades of sodium chloride solids; and feeding the screened tail salt slurry into the solid-liquid separation device M4.
Optionally, after the thickener M1 thickens the tail salt slurry, the solid phase volume concentration of the tail salt slurry is increased to 45% to 55%.
Optionally, the supernatant produced in the thickener M1 is returned to the salt pan for the production of carnallite again.
Optionally, the amount of fresh water added to the washing tank M2 is based on the content of potassium chloride and is based on KCl-NaCl-MgCl2-H2And (4) calculating the water quantity of the dissolved potassium chloride by using an O quaternary water-salt system phase diagram.
Optionally, a fresh water rinse is added to the screening process of the screening device M3 to reduce the mother liquor entrained in the solid phase.
Optionally, the screening device M3 comprises one of a vibrating screen, a rotating screen, a stationary screen.
Optionally, the different grades of sodium chloride solids are dewatered by means of heap filtration to obtain dried sodium chloride solids for use by the industrial soda industry.
Optionally, the solid-liquid separation device M4 comprises one of a centrifuge, a plate and frame filter, a bag filter, a belt filter.
Optionally, the solid-liquid separation device M4 adds a fresh water rinse in the solid-liquid separation process to reduce the mother liquid entrained in the solid phase.
Optionally, the potassium-containing filtrate is returned to the salt pan for the production of carnallite again.
The system of the present invention has been described and explained in detail above in connection with the method, and will not be described in detail here.
The following is a description of specific experimental test data for one embodiment. For example, 2500mL of concentrated direct flotation tailing slurry with a volume concentration of 55% is taken, and the compositions of the components in the solid phase and the liquid phase are shown in Table 1; taking 2500mL of the same concentrated tail salt slurry, adding 250mL of fresh water into the concentrated tail salt slurry to wash and dissolve carnallite particles for further purification, and then continuing to process the sample obtained according to the technical scheme of the invention, wherein the composition of the solid phase and the liquid phase is shown in Table 2. The solid phase composition in table 2 is a composition of the fractionated solid phase obtained in the sieving step and the solid phase obtained in the solid-liquid separation step. The silt content in the tail salt slurry in the embodiment is less.
TABLE 1
| Sample composition | KCl(％) | NaCl(％) | MgCl2(％) | CaSO4(％) | Weight (kg) |
| Solid phase | 0.1 | 95.7 | 0.8 | 1.1 | 1.1 |
| Liquid phase | 4.7 | 4.6 | 18.1 | 0.6 | 2.6 |
TABLE 2
It can be seen from the data in tables 1 and 2 that the mass fraction of sodium chloride in the solid phase obtained from the positive flotation tail salt slurry treated by the technical scheme of the present invention is obviously increased from 91.1% to 95.7%, that is, the slurry solid phase not treated by the technical scheme of the present invention cannot be used for the production of industrial soda ash, and the solid phase sodium chloride treated by the technical scheme of the present invention can meet the requirements of the production of industrial soda ash. The technical scheme of the invention can effectively improve the utilization rate of the direct flotation tail salt resource.
The technical scheme of the invention has the advantages that:
1) according to the technical scheme of the invention, potassium chloride in the direct flotation tail salt can be recycled, and sodium chloride can be classified according to market condition requirements, so that the waste of resources is avoided, and the utilization rate of the direct flotation tail salt resources is greatly improved;
2) the technical scheme of the invention has simple process flow and can produce sodium chloride products with different grain size grades.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.
Claims (20)
1. A direct flotation tail salt recovery processing method, wherein the direct flotation tail salt is slurry comprising sodium chloride and carnallite particles, the method comprises the following steps,
thickening step (S1):
sending the tail salt slurry to a thickener for thickening so as to improve the concentration of the tail salt slurry;
washing step (S2):
sending the concentrated tail salt slurry to a washing tank, adding fresh water into the washing tank, and washing under the stirring action to dissolve carnallite particles in the tail salt slurry;
a screening step (S3):
screening the washed tail salt slurry by adopting screening equipment, and grading the solid phase obtained by screening by different particle sizes to produce sodium chloride solids of different grades;
performing solid-liquid separation on the screened tail salt slurry (S4);
solid-liquid separation step (S4):
and carrying out solid-liquid separation on the screened tail salt slurry by adopting a solid-liquid separation device to obtain a solid phase containing sodium chloride and a filtrate containing potassium.
2. The method of claim 1, said thickening step (S1) further comprising increasing the solids volume concentration of the tailings slurry to 45-55% after thickening by the thickener.
3. The method of claim 1, wherein the step of concentrating (S1) further comprises returning supernatant produced in the thickener to the salt pan for re-production of carnallite.
4. The method according to claim 1, wherein the washing step (S2) further comprises calculating the amount of water for dissolving the potassium chloride based on the amount of potassium chloride by using a KCl-NaCl-MgCl2-H2O quaternary water salt system phase diagram.
5. The method of claim 1, wherein said step of screening (S3) further comprises adding a fresh water rinse to the screening device during screening to reduce entrained mother liquor in the solid phase.
6. The method of claim 1, said screening step (S3) further comprising said screening apparatus comprising one of a vibrating screen, a rotating screen, a stationary screen.
7. The method of claim 1, said screening step (S3) further comprising dewatering said varying grades of sodium chloride solids by heap filtration to obtain dried sodium chloride solids for use by the industrial soda industry.
8. The method of claim 1, the solid-liquid separating step (S4) further comprising the solid-liquid separating device comprising one of a centrifuge, a plate and frame filter, a bag filter, a belt filter.
9. The method of claim 1, the solid-liquid separating step (S4) further comprising: and adding fresh water for leaching in the solid-liquid separation process of the solid-liquid separation device to reduce the mother liquor carried in the solid phase.
10. The method of claim 1, the solid-liquid separating step (S4) further comprising: and returning the potassium-containing filtrate to the salt pan to produce the carnallite again.
11. A direct flotation tail salt recovery processing system, wherein the direct flotation tail salt is slurry containing sodium chloride and carnallite particles, the system comprises,
the thickener is used for receiving the tail salt slurry and thickening the slurry so as to improve the concentration of the tail salt slurry;
the washing tank is connected behind the thickener, receives the thickened tail salt slurry, adds fresh water and washes the tail salt slurry under the stirring action so as to dissolve carnallite particles in the tail salt slurry;
the solid-liquid separation device is connected behind the washing tank, receives the washed tail salt slurry and performs solid-liquid separation to obtain a solid phase containing sodium chloride and a potassium-containing filtrate;
the screening equipment is connected between the washing tank and the solid-liquid separation device, receives and screens the washed tail salt slurry, and performs classification of different particle sizes on the solid phase obtained by screening to produce sodium chloride solids of different grades; and feeding the screened tail salt slurry into the solid-liquid separation device.
12. The system of claim 11, wherein the thickener increases the solids volume concentration of the tailings slurry to 45% to 55% after thickening the tailings slurry.
13. The system of claim 11, wherein supernatant produced in the thickener is returned to the salt pan for re-production of carnallite.
14. The system of claim 11, wherein the amount of fresh water added to the wash tank is calculated based on the amount of potassium chloride, based on a phase diagram of a KCl-NaCl-MgCl2-H2O quaternary water salt system.
15. The system of claim 11, further comprising adding a fresh water rinse to the screening device during screening to reduce entrained mother liquor in the solid phase.
16. The system of claim 11, further comprising the screening device comprising one of a vibrating screen, a rotating screen, and a stationary screen.
17. The system of claim 11, further comprising dewatering the different grades of sodium chloride solids by heap filtration to obtain dried sodium chloride solids for use by the industrial soda industry.
18. The system of claim 11, further comprising the solid-liquid separation device comprises one of a centrifuge, a plate and frame filter, a bag filter, a belt filter.
19. The system of claim 11, further comprising adding a fresh water rinse to the solid-liquid separation device during the solid-liquid separation process to reduce the mother liquor entrained in the solid phase.
20. The system of claim 11, further comprising returning the potassium-containing filtrate to the salt pan for re-production of carnallite.
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