RU2699287C1 - Device for dry beneficiation of gold ores - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to means of dry concentration of mineral raw materials. Device for dry enrichment of gold-bearing ores contains a raw material supply unit, a raw material particles acceleration unit and a ready product reception unit. Unit for acceleration of particles of raw material is made in the form of drum equipped with blades and connected to shaft of electric motor. Finished product reception unit is made of perforated sheets with air-permeable coating.

EFFECT: reduction of losses of fine fractions of gold at enrichment of gold-bearing ores, and also reduction of power inputs and increase of labour productivity.

1 cl, 1 dwg, 2 tbl

Description

The invention relates to dry enrichment of mineral raw materials.

Dry enrichment has advantages over other technologies that use water, other solvents and chemicals, because there is no need for subsequent drying and cleaning of the finished product, sludge collectors.

For dry enrichment, the following are used: detection of the desired product by secondary radiation (RU No. 2131781, publ. 06/20/1999), sequential isolation and dispersion of products by the linear particle size (US 43754554, publ. 01.03.1983, US 5470554, publ. 28.11.1995 , RU 2390380, publ. May 27, 2010), separation of products by mass of particles when moving along an inclined plane (RU 2142859, publ. 12/20/1999, RU 2292243, publ. 03/15/2007), centrifugal-shock separation followed by dry magnetic separation (RU 2381079, publ. 02/10/2010, RU 2370326, publ. 10/20/2009). A technology based on the difference in the time of soaking of light and heavy particles of raw materials (RU 2309804, publ. 10.11.2007) and a device including preliminary vibration of the material and subsequent separation of particles in the concentration element according to the aerodynamic resistance of particles moving along a smooth and porous surface are also used ( RU 2374002, published on November 27, 2009).

The closest analogue is a device for dry enrichment of mineral raw materials, containing a unit for grinding the starting material to the required size, a pneumatic nozzle to give the particles initial velocity and a receiving device that includes a region of passage of particles and receiving containers separated by partitions (RU 2472593, published on 01.20.2013).

The disadvantages of this device are significant energy consumption for the formation of a stream of air-dust mixture, distortion of the particle’s flight paths by a large stream of air, and the loss of a fine fraction of raw material particles.

The objective of the invention is to reduce energy consumption for dispersing particles of raw materials and material losses in the receiving device, increasing the productivity of equipment for ore processing.

The technical result of the invention is the direct production of highly enriched gold concentrate without loss of fine fractions, at low energy costs.

The technical result is achieved by the fact that the dispersal of particles is carried out mechanically, and the region of passage of particles and their reception is protected by sheets of perforated material with a breathable coating.

The invention is illustrated in the figure, where:

1. The capacity into which the source mineral raw materials of the required size are supplied;

2. Slotted feed channel;

3. Accelerating drum rotating clockwise;

4. The blades of the booster drum;

5. Electric drive shaft;

6. The upper part of the receiving device;

7. Capacities for receiving the final product.

In the figure, the coordinates of the particles are indicated as x and y, their positive value in the direction of the arrows. The origin is point 0 on the x axis.

The operation of the device is based on the difference in ballistic trajectories for particles of different sizes and densities.

The feedstock from the tank 1 through the slotted channel 2 is fed to a drum 3 with a diameter D (around the circumference of the blades 4), which rotates with a frequency ϕ, and the particles of the raw material with an initial speed v ₀ = π⋅D⋅ϕ move in region 6 until they reach the receiving capacity 7. The dependence of the x and y coordinates on time t is described by the formulas:

In these expressions:

ρ is the particle density;

- линейный размер (крупность) частицы;

- linear size (particle size) of the particle;

d is the density of air;

g is the acceleration of gravity.

The initial direction of particle motion is parallel to the horizon.

It is advisable to grind the initial ore to a grain size of not more than 10 mm. For this purpose, you can use, for example, a Metso NRZ crusher with a capacity of up to 100 t / h. Next, on screens, divide by particle size into fractions of 0.4-0.5 mm, 0.5-0.6 mm, 0.6-0.7 mm, 0.7-0.8 mm, 0.8-0.9 mm , 0.9-1 mm, 1-2 mm, 2-3 mm, 3-4 mm, 4-5 mm, 5-6 mm, 6-7 mm, 7-9 mm, 8-9 mm and 9- 10 mm. Fractions of smaller size should be enriched with traditional technologies.

With a drum diameter of 0.5 m and a rotational speed of the bearing shaft of 1500 rpm, the initial velocity of particles of any size will be about 40 m / s.

Below are the coordinates of particles with a particle size of 0.4 mm to 10 mm at time t = 0.5 s, at an initial speed of 40 m / s for both pure gold particles and intergrowths with rock minerals, including gangue. These particles will have a true density of from 2000 kg / m ³ to 19000 kg / m ³ . The left column shows the particle density reduced by 1000 times. Particle coordinates are indicated in meters.

The gold contained in the ore is found mainly in the form of small grains ranging in size from fractions of a millimeter to several millimeters, or in the form of aggregates with minerals of ore. Physically, ore is a combination of several minerals. For analysis, the chemical composition of the ore is usually studied by measuring the content of various elements and then converting to oxides. Here is the composition of one of the typical quartz gold ores.

The average density of ore is about 3000 kg / m ³ , while the density of gold particles is 19000 kg / m ³ , and this allows, according to the coordinate table, it is easy to separate gold in the stream with gangue, or with rock with a low gold content .

The device operates as follows. The crushed ore crushed in a crusher to a particle size of less than 10 mm and screened after screening from a tank 1 is fed through a slotted channel 2 to a booster drum 3 provided with blades 4. The shaft of the booster drum 5 is connected through a gearbox to the motor shaft. The initial separation rate of an ore particle from a drum blade is controlled by the engine speed. The optimum value is 40 m / s. Then the particles fall into the upper part of the receiving device 6, move along ballistic trajectories, in accordance with their size and density, and fall into different receiving containers 7. Gold and highly enriched ore particles will sink into more distant containers. In order to avoid losses of small fractions of ore that inevitably occur during mechanical action on the ore, the entire receiving device, including the receiving containers of the finished product, is made of perforated metal coated with breathable fabric or paper. This device can be used for gold ores of any mineral and chemical composition. In this case, it is necessary to carry out preliminary calibration, which consists in the location of the receiving tanks and the initial velocity of separation of particles from the drum.

The energy intensity of the device is significantly less than other traditional technologies. The total energy costs, including crushing, calibration and enrichment, do not exceed 7 kWh / t.

The gold recovery factor for quartz ores is about 85%. Ore productivity approx. 50 t / h. Gold performance for ore, the chemical composition of which is given above, will be about 1 t / year. Capital costs for a set of equipment pay off in less than a month.

Claims (1)

A device for dry beneficiation of gold ores containing a feed supply unit, a feed particle dispersal unit and a finished product receiving unit, characterized in that the feed particle dispersal unit is made in the form of a drum equipped with blades and connected to an electric motor shaft, and the finished product receiving unit is made of perforated sheets with breathable coating.

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