RU2035228C1 - Mill for wet self-crushing of diamond containing raw materials - Google Patents

Abstract

FIELD: diamond extracting industry. SUBSTANCE: mill has a drum with charging and discharging mechanisms, and collector for crushed material. The discharging mechanism is made in the form of grated windows located along the cylindrical surface of drum, with each window being a little bit shifted relative to its predecessor. EFFECT: higher efficiency and reliability. 1 cl, 1 dwg

Description

 The invention relates to the field of mineral processing, in particular to the design of wet self-grinding mills, in which grinding is carried out by pieces of the original ore, and can be used in the diamond mining industry in preparing ores for processing.

 Known mill [1] wet self-grinding ores of ferrous and non-ferrous metals, including a drum with loading and unloading devices and a collection of the finished product. The unloading device is a grill mounted on the front side of the drum.

 The disadvantage of this mill is that when grinding diamond-containing raw materials in it, the valuable component and ore material are regrind due to the excessive residence time of diamonds and finished material in the mill drum. This reduces the preservation of the natural quality of diamonds and, therefore, reduces their price. In addition, there is an additional energy consumption for unnecessary regrinding of the finished product.

The closest in technical essence and the achieved result and adopted for the prototype is a mill [2] wet self-grinding diamond-containing raw materials, including a drum with loading and unloading devices and a collection of the finished product. The unloading device is a three-tier grate installed on the front side of the drum, the inner tier of which with a diameter equal to 0.4-0.8 of the diameter of the drum is blind, and the middle tier is made with a live section coefficient in the range of 0.1-0.4. The height of the peripheral tier of the lattice is 0.05 of the diameter of the drum, and its live section coefficient is determined from the relation: KK _e ˙ L, where K is the coefficient of the live section of the peripheral tier of the lattice; To _{e the} coefficient of proportionality, characterizing the coefficient of living section of the peripheral tier of the lattice of the reference mill with a drum length of 1 m equal to 0.02 m ^-1 ; L drum length, m.

 The disadvantage of this mill is that although it provides a certain reduction in overgrowing of diamonds by mitigating impact loads by maintaining a certain level of material smaller than the size of the openings of the discharge grate, it is not possible to avoid a sufficiently damaged diamond. This is due to the fact that unloading is carried out through the end diaphragm grate, and with this unloading, the direction of movement of the crushed particles and open diamonds to the slots of the unloading grate does not coincide with the trajectory of the ore loading in the drum, therefore, the output speed of the crushed material is low. Untimely withdrawal of open diamonds from the mill increases the risk of damage. In addition, there is an overspending of electricity.

 The purpose of the invention is the creation of a mill, which allows to increase the preservation of the natural quality of diamonds and reduce the specific energy consumption by increasing the discharge speed of the crushed material and open diamonds.

где К поправочный коэффициент, значения которого лежат в интервале 0,8-1,2;
S_ж.сеч. суммарная площадь живого сечения отверстий разгрузочных решеток, м²;
Q объемная производительность мельницы, м³/ч;
D диаметр мельницы, м.This is achieved by the fact that in a wet self-grinding mill of diamond-containing raw materials, including a drum with loading and unloading devices and a collection of crushed material, according to the invention, the unloading device is made in the form of windows with gratings located uniformly along the cylindrical surface of the drum with each window shifted relative to the previous one, with this total living area of the discharge grids is determined from the ratio:
S _{train station} = K

where K is a correction factor whose values are in the range of 0.8-1.2;
S _{train station} the total living area of the openings of the discharge grills, m ² ;
Q volumetric productivity of the mill, m ³ / h;
D mill diameter, m

 The ratio is obtained empirically, i.e. Numerous experimental tests have selected a ratio that ensures timely removal of open diamonds from the mill and does not reduce the rigidity of the mill.

где l длина разгрузочного окна, м;
L длина барабана, м;
n число окон по длине барабана.The length of the discharge window is determined from the ratio
l

where l is the length of the discharge window, m;
L drum length, m;
n is the number of windows along the length of the drum.

 With this ratio of the length of the discharge window and the length of the drum, the formation of dead zones in the drum is excluded.

 A comparative analysis of the claimed device and prototype allows us to conclude that the claimed technical solution meets the criterion of "novelty."

Comparison with other technical solutions included in the "prior art" showed that it is known a device for grinding lumpy and coarse-grained material, in which the discharge of crushed material occurs on the cylindrical surface of the drum [3]
However, in this device, podkolosniki beams are located along the entire cylindrical surface of the drum and are divided into fixed distance rods and grate elements. This design of the mill is not reliable in operation, especially with a large drum volume. In addition, when used for self-grinding of diamond ores, the circulating load will increase significantly. This is due to the specifics of the enrichment of diamond ores containing diamonds with a grain size of 0.2-30 mm, and the need to extract them while preserving the natural size and quality. To do this, the technological schemes of diamond-extraction factories provide for the disintegration of kimberlites up to 2 mm in a detailed scheme for the enrichment of crushed ore material of all particle sizes from 0.5 + 0.2 mm to 30/50 / + 16 mm, and they are returned to the grinding mill as a circulating load only tailings (larger than 2 mm). Therefore, an increase in the value of the circulating load inevitably entails an increase in the front of classification, screening and ore beneficiation.

 In the inventive mill, the execution of the discharge device in the form of windows with gratings located uniformly along the cylindrical surface of the drum with a shift relative to each other and having an optimal living cross-sectional area will provide not only a high output rate of the crushed material without regrinding, but will not lead to large growth circulating load. In addition, this design of the mill is very stiff and, therefore, reliable in operation.

 Thus, the set of essential features will ensure the implementation of the objectives of the invention, because Due to the acceleration of the removal of open diamonds and crushed ore material from finished grains from the mill drum, over-grinding of diamonds can be avoided, which will significantly reduce the proportion of diamond crystals that have cracked, split or lost mass, and thereby preserve their natural quality and cost.

, исключает образование мертвых зон в барабане мельницы, т. е. измельченный материал разгружается равномерно по всей длине барабана мельницы.This effect is reinforced by the fact that the choice of the length of the discharge window, determined from the relation l

, eliminates the formation of dead zones in the mill drum, i.e., the crushed material is unloaded uniformly along the entire length of the mill drum.

 Reducing the residence time of the finished product in the mill provides a reduction in the specific energy consumption for grinding ore.

 The above allows us to conclude that the claimed technical solution meets the criterion of "inventive step".

 The drawing shows the proposed mill.

 The wet self-grinding mill of diamond-containing ores contains a drum 1, in which the end wall 2 is made integral, and the end wall 3 has a loading hole. On the cylindrical surface of the drum 1 at an equal distance from each other there are windows 4 with gratings located with a shift of each subsequent window relative to the previous one.

Для загрузки исходной руды в барабан 1 служат бункер 5 и цапфа 6, а для приема измельченного материала сборник 7. Барабан 1 снабжен ребрами жесткости 8 для крепления к цапфам 5.In this example, the windows 4 are arranged in two rows along the length of the drum 1, so the length of the window 4 is half the length of the drum 1. The total area of the "live" section of the gratings is determined from the ratio
S _{train station} = K

To load the original ore into the drum 1, the hopper 5 and the trunnion 6 are used, and to collect the crushed material, the collector 7. The drum 1 is equipped with stiffeners 8 for fastening to the trunnions 5.

 The mill operates as follows.

 In the rotating drum 1 from the hopper 5 through the pin 6 and the loading hole in the end wall 3 serves pieces of the original ore and water. The material entering the drum 1 is captured by lifters (not shown) and rises up until the radial component of gravity exceeds the centrifugal force, after which the pieces of ore fall down and hit each other. There is a constant mixing of the material, during which it is crushed by cracking, crushing and abrasion. The crushed material, the size of which becomes smaller than the slit of the discharge grill of the windows 4, together with water passes through the slots into the collector 7 and is discharged from the mill. The direction of movement of the crushed material to the discharge grill in the drum 1 of the mill coincides with the direction of movement of the ore load, which increases the output rate of the crushed material.

 To determine the prospects of using the mill of the claimed design, comparative tests were carried out to grind kimberlite ore on semi-industrial samples of two mills: according to the prototype and according to the invention. The tests were carried out under equal conditions on the same ore. The test results are presented in the table.

 Tests have confirmed the compliance of the claimed device with the criterion of "industrial applicability".

 Using the proposed mill will ensure timely withdrawal of crushed material from the drum, halving the time spent by diamonds in the mill. This will increase the safety of diamonds, reducing on average by half the risk of cracks, chips, splits and more significant destruction of diamond crystals. Loss of diamonds in bulk decreases from 0.95 to 0.02%; loss in value of diamonds from 0.76 to 0.03%; Specific energy consumption decreases by 30%; mill productivity increases by 80%

Claims (2)

1. MILL OF WET SELF-GRINDING DIAMOND-CONTAINING RAW MATERIALS, including a drum with loading and unloading devices and a collection of ground material, characterized in that the unloading device is made in the form of windows with gratings located uniformly along the cylindrical surface of the drum with each window shifted relative to the previous one, with the total area "live" section S z.sech. discharge grills determined from the ratio

where K is a correction factor;
Q volumetric productivity of the mill, m ³ / h;
D mill diameter, m 2. Mill according to claim 1, characterized in that the length l of the discharge window is determined from the relation
l L / n
where L is the length of the drum, m; n the number of discharge windows along the length of the drum.

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