Selection and application of washing equipment

Beneficiation plant (or plant crushing sieve) under the following conditions, to consider setting washing operations:

(1) When processing ore containing more mud and containing water, it is easy to block the mine silo, chute, funnel and crushing and screening equipment , which affects the normal production.

(2) For some ores, the ore can be removed by washing, and the useful minerals are enriched and qualified products are obtained. For example, some of the deposition of manganese ore, apatite, iron-rich ore and limestone and the like.

There are many types of washing equipment. Commonly used are cylindrical washing machines, screen scrubbing machines, tank washing machines, and hydraulic washing screens. In addition, many screening equipment (such as fixed screens, roller screens, vibrating screens, etc.) and spiral classifiers can also be used as mineral processing equipment.

The choice of washing equipment and its throughput depends mainly on the washability of the ore. The washability of the ore can be assessed according to indicators such as clay plasticity index, washing time, specific energy consumption and washing efficiency. The relationship between the washability of ore and the use of washing equipment is shown in Table 1.

Table 1 Relationship between ore washability and optional washing equipment

1. Cylinder washing machine (also known as cylinder washing machine)

This equipment is used for washing and screening operations and is suitable for the treatment of easily washable and medium washable ores. The mesh size can be as small as 8mm and up to 50mm, and the cylinder screen is installed obliquely. The equipment has simple structure, easy maintenance and management, and stable work, but the handling amount per unit area is small, the effective working sieve surface is small, the screening efficiency is low, and the screen surface is easy to wear.

The equipment is widely used in pre-selection operations on gold mining vessels. The mesh size can be equal to the diameter of the mesh, and the difference can be used (the difference in the size of the mesh from the feeding end to the discharge end of the product on the screen). There are high pressure flushing water pipes, material blocking rings and lifting plates. The large mesh cylinder washing machine for limestone mining is often used in combination with a tank washing machine for two-stage scrubbing. The first stage uses a cylindrical washing machine, and the second stage uses a tank washer to scrub the product under the screen.

The processing capacity of the cylinder washing machine can be calculated according to the formula recommended by the former Soviet Union Soviet Union Scientific Research and Design Institute:

q=110K _a K _L R ₃ ntga (1)

Where q - cylinder washing machine processing capacity, t / h;

K _a —— the effective area influence coefficient of the mesh, selected according to Table 2 and Table 3;

K _L - the influence coefficient of the length of the sieve hole section, see Table 4;

R——tube sieve radius, m;

A——the inclination angle of the cylinder screen, (°);

N——the number of cylinder screen revolutions, r/min, when sieving

Table 2 to mesh with a sieve area of the effective area _{(A a} / A) K _a relationship between

Table 3 Relationship between mesh size and A _a /A

Punching size / mm	8	10	12	14	16	18
(A a /A)/%	17.1	18.2	21.3	22.2	23.4	24.6

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Table 4 The ratio of the length of the sieve segment to the diameter of the sieve (L/D) and K _L

See Table 5 for examples of cylinder washing production.

Table 5 Production examples of cylinder washing machine

Second, with a screen scrubber

The screen scrubber consists of a closed cylinder and a double cylinder screen attached to the end of the cylinder. The slurry is soaked in water in the cylinder and collides and rubs against each other during the rotation to dissociate the clay and the ore. At the same time, the high-pressure water is introduced to wash the slime; the slurry is passed through a double-layer sieve to divide the material into coarse, medium and fine three grains. Grade, fine particle product combined with washing overflow. The equipment has high washing efficiency and can complete the double tasks of washing and sieving at one time. It is suitable for medium washable and difficult to wash ore, but it is not suitable for processing ore with less ore and mud. See Table 6 for the operating conditions and treatment capacity of a concentrating plant with screen scrubbing.

Table 6 Operating conditions and throughput of a washing machine with a screen

project	unit	Numerical value
Simplified size, inner diameter × length	Mm	1120×3620
Barrel size, long Sieve	Mm Mm	1070 Inner layer; 25, outer layer; 5
Installation power	kW	22.5
Processing capacity	t/d	600~700
Feeding maximum particle size	Mm	100
Washing particle size limit	Mm	2.0
Overflow - 2mm content	%	80~85
-2mm content in sand	%	5~10
Washing efficiency	%	80~85

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Third, trough type washing machine (also known as trough scrubber)

The device is similar in construction to a spiral classifier, except that the blades are discontinuous blade shapes. It has the function of cutting and scrubbing the material, and has strong effect on the small mud group. It is suitable for the treatment of difficult-washed ore with medium grain size and more mud. The equipment has large processing capacity and high washing efficiency, and is suitable for processing materials below 75mm. The flushing water pressure is required to be 147~196kPa. The production example of the tank washing machine is shown in Table 7.

Table 7 Production example of tank washing machine

Fourth, hydraulic washing sieve (also known as hydraulic washing or water gun - strip screen)

Hydraulic wash griddle suitable for processing with mud pie and more difficult to wash ore, tin ore sand mining water is used more often washing water transport facilities. See Table 8 for the technical parameters and operating conditions of the hydraulic washing screen of a slope sand and tin ore dressing plant in Yunnan.

Table 8 Technical parameters and operating conditions of hydraulic washing screen

The grid sieve, the rod sieve, the roller screen and the vibrating screen can be used as a washing equipment after being equipped with a pressure flushing water pipe, and is suitable for treating ore having a small amount of mud and a weak cohesiveness.

The spiral classifier can be used to de-sludge and dewater the fine-grained products discharged from the washing machine. Its fragmentation effect is not strong, and it is not suitable for the treatment of ore with large mud and large viscosity.