RU2733878C1 - Method and device for disintegration of gold-bearing clay rocks - Google Patents

Abstract

FIELD: enrichment of minerals.

SUBSTANCE: invention relates to a method and apparatus for extracting fine gold from clayey gold-bearing rocks. Device for vacuum disintegration of gold-bearing clay rocks includes working chamber and receiver, volume ratio of which is <1:200, vacuum pump performance ≥0.5 m³/s, connected to the receiver, fast acting pneumatic valves and pumping lapping atmosphere. Working chamber comprises a clay rock tray which is equipped with a heater with adjustable power of up to 200 W and three temperature sensors, made with possibility of installation at different depth of rock thickness. Pulse rate evacuation is carried out for not more than 1 s with pressure in working chamber of 0.4 kPa and subsequent reduction to 13 Pa for not more than 10 s at operating vacuum pump. Clay rock in the form of a flat layer with thickness of 1–5 cm is placed in a tray for clay rock and held at vacuum for 20 s, then during 20 s, the atmosphere is introduced, followed by holding at atmospheric pressure for 20 s. Pumping-admission cycle is repeated until rock freezes, which occurs during evacuation due to intensive evaporation of moisture from rock, after which for 10 minutes the heater is defrosted and temperature is raised to room temperature. Process of freezing-heating is repeated until the remaining amount of moisture becomes insufficient for freezing of the rock, at that, from 2 to 10 pumping-let-down cycles are performed.

EFFECT: invention enables to intensify the process and increase the efficiency of gold-containing clay rocks disintegration.

4 cl, 1 dwg

Description

The invention relates to the beneficiation of minerals, in particular to apparatuses for extracting fine gold from clay gold-bearing rocks.

It is known that after beneficiation, a significant gold content can remain in the tailings of clayey gold-bearing rocks. It is also known that tailings dumps that have been laid out in the open air for several years become a rock from which gold mining can be economically viable. The reason is that freezing the rock in the winter and thawing it in the summer lead to the disintegration of the rock.

However, the natural defrosting process takes a considerable amount of time. The present invention is directed to the intensification of this process in vitro.

A known installation for thermal vacuum-pulse drying of food materials (RF patent No. 166946, 2016, F26B 9/06, F26B 5/04, F26B 3/04, F26B 21/04), which includes two drying chambers connected by pipelines with quick-acting valves with a receiver, and a liquid ring vacuum pump connected to the receiver. Each drying chamber is equipped with a gaseous heat carrier conditioning system and a convective heating system for materials with recirculation of the gaseous heat carrier. According to the signals from the temperature and humidity sensors located in the drying chamber, the temperature of the walls of the drying chambers and the material is brought to 45 ° C, and the temperature and relative humidity in the chamber to 45-50 ° C and 50%, respectively. Electric tape flexible heaters (ENGLs) are used for thermostating the surfaces of drying chambers. In the receiver, the vacuum is brought to a value of ~ 1 kPa. Cycles "heating-evacuation" are periodically repeated until the required moisture content of this or that material is reached.

The disadvantages of this solution are:

- large, in comparison with the receiver, the volume of working chambers, which accommodate multi-level mobile carts with shelves or hangers;

- the presence of a heat pump for cooling the water circulating in the liquid ring pump, which complicates and increases the cost of the entire structure;

- complex design of working chambers designed for drying with heating;

- the ultimate vacuum is 1 kPa, which is significantly higher than the pressure of saturated water vapor at the freezing point (~ 500 Pa);

- heating of samples is carried out due to the walls of the drying chamber;

- the level of relative humidity in the installation is 50%, which significantly exceeds the values for pulse evacuation in the claimed device (about 1%).

A known method of drying wood (RF patent No. 2400684,2009, F26B 5/04, F26B 9/06). The installation that implements the method of wood drying includes two drying chambers connected by pipelines with quick-acting valves with a first cooled receiver with a lock chamber connected in series with the second receiver and with a vacuum pump by means of a pipeline with a vacuum seal. The method for drying wood includes multiple alternation of cycles, including blowing wood with a coolant with heating it to an average volume temperature of 80-100 ° C, pulsed (high-speed) evacuation using a receiver, high-speed valves and pipelines, followed by holding under vacuum, blowing wood is carried out at atmospheric pressure, impulse evacuation is carried out in a time of no more than 10 seconds with the squeezing of free moisture from wood without a phase transition of liquid water to steam with holding under vacuum to a steady constant value of the wood temperature, after which the vacuum is released to atmospheric pressure by supplying a coolant, and the wood is blown and the vacuum released carried out with an air heat carrier with a temperature of 150-300 ° C, and at the beginning and end of the drying process, one or more drying cycles are additionally carried out using steam with a temperature of 100-115 ° C as a heat carrier at an excess pressure of not higher than 0.07 MPa. Evacuation is carried out at a working pressure of no more than 50 mm Hg.

The disadvantages of the solution are:

- complex design of working chambers designed for drying with heating;

- heating of the samples is carried out due to the gas coolant, the temperature of the air coolant is 150-300 ° C, which requires a lot of energy;

- insufficiently high ultimate vacuum (about 7 kPa);

- vacuuming time up to 10 sec.

A known method of drying wood (RF patent No. 2468319, 2009, F26B 5/04, F26B 9/06). The installation for the implementation of the method contains at least two sealed drying chambers, a vacuum pump and a receiver, connected by a pipeline with sealed flaps. The method for drying wood includes multiple alternation of blowing wood with a heat carrier with heating the wood to a temperature of 80-100 ° C, evacuation using a vacuum pump, receiver and pipelines with sealed dampers. The method is carried out as follows: a vacuum is created in the receiver with a vacuum pump to 0.90 atm, after which the pump is turned off, the receiver is connected with the drying chamber using the shutters, the time is maintained for which the vacuum in them is compared, then the vacuum pump is turned on and brought in the drying chamber vacuum to 0.90 atm, then with the help of dampers disconnect the drying chamber from the receiver, maintain a time (60-70 min), during which the vacuum in the chamber decreases to 0.30 atm, and during this time the vacuum in the receiver is again brought to 0.90 atm and again connect the receiver to the drying chamber, maintain the time during which the vacuum in the chamber and in the receiver is compared, turn on the vacuum pump and bring the vacuum in the drying chamber to 0.90 atm, disconnect the receiver from the drying chamber and repeat the previous operations.

The disadvantages of the solution are:

- complex design of working chambers;

- heating of samples is carried out by means of a gas coolant;

- low ultimate vacuum (about 30 kPa);

- the evacuation time is 60-70 minutes.

The closest in technical essence to the claimed method is a method of vacuum disintegration of gold-bearing clay rocks (RF patent No. 2693586, 2018, С22В 11/00, В03В 7/00), in which a pulsed vacuumization of the working volume is carried out, in which the gold-bearing clay rock is located ... The effect of rock disintegration is achieved both by cooling, up to freezing, and by mechanical deformation due to the expansion of the rock with a sharp drop in ambient pressure.

The disadvantage of this solution: the processed material has a shape close to spherical, as a result, the freezing time of the material increases, the freezing process takes place in the first vacuum cycle and the next cycle takes time to defrost. All this reduces the efficiency of disintegration.

The closest in technical essence to the claimed device is a device for vacuum disintegration of gold-bearing clay rocks (RF patent No. 2686976, 2018, С22В 11/12, В03В 7/00, С22В 7/00, 2018), containing a receiver, a vacuum pump connected to the receiver, the working chamber.

The disadvantage of this device is the lack of a constructive possibility of intensifying the process of defrosting the rock.

The objective of the invention is to intensify and improve the efficiency of disintegration of gold-bearing clay rocks in order to increase the yield of ultrafine particles of precious metals when they are extracted from gold-bearing clay rocks.

The problem is solved by the fact that in the method of vacuum disintegration of gold-bearing clay rocks, including impulse high-speed evacuation in a time of no more than 1 second with a pressure in the working chamber of 0.4 kPa and a subsequent decrease to 13 Pa in a time of no more than 10 seconds with a working vacuum pump According to the invention, the rock is kept under the influence of vacuum for 20 seconds, then the atmosphere is puffed in for 20 seconds, the rock is kept at atmospheric pressure for 20 seconds, then the pumping-puffing cycle is repeated until the rock freezes, after the rock freezes, the heater is turned on, which after a time of 10 minutes leads to thawing of the rock and a rise in temperature to room temperature, the freezing-heating process is repeated until the remaining amount of moisture becomes insufficient to freeze the rock. The clayey rock has a flat shape with a layer thickness of 1-5 cm and a transverse dimension exceeding the thickness by 5-30 times. The number of cycles depends on the thickness of the clay layer and is for a given time cycle from 2 (for a thickness of 1 cm) to 10 (for a thickness of 5 cm).

The problem is solved by the fact that in a device for vacuum disintegration of gold-bearing clay rocks, containing a working chamber and a receiver, the volume ratio of which is <1: 200, a vacuum pump with a capacity of ≥ 0.5 m ³ / s, connected to the receiver, high-speed pneumatic valves for pumping out and letting in the atmosphere, according to the invention, the working chamber contains a sump for clay rock, which is equipped with a heater with adjustable power from 0 to 200 W.

Vacuuming leads to intensive evaporation of moisture from the rock, which, in turn, due to the heat of phase transition, leads to cooling of the rock until freezing. However, the natural defrosting process takes a considerable amount of time. For quick defrosting of the rock, a heater with adjustable power (0-200 W) is built into the rock pan. An increase in the efficiency of disintegration of gold-bearing rock is achieved both due to a change in the shape of the processed rock and due to the fact that several cycles of mechanical disintegration occur during the time required for the freezing of the rock (when the rock expands during impulse evacuation and when the rock is compressed with pulsed air inlet atmospheric pressure).

The differences between the new method of disintegration of gold-bearing clayey rock are: 1) periodic admission of air to atmospheric pressure even before the rock freezes; 2) to increase the evaporation area, the clayey rock has a flat shape, in which the thickness is significantly less than the transverse dimensions.

FIG. 1 shows a device for vacuum disintegration of gold-bearing clay rocks, where:

1 - receiver;

2 - pressure sensor;

3 - pressure indication unit;

4 - working chamber;

5 - pressure sensor;

6 - ADC;

7 - computer;

8 - control unit;

9 - pallet;

10 - temperature sensors;

11 - heater;

12 - power supply for the heater;

13 - valve for inlet atmosphere;

14 - pumping valve;

15 - vacuum pump.

The method is carried out as follows.

The processed rock is placed in a special waterproof pallet 9 in the working chamber 4 in the form of a flat layer 1-5 cm thick and the chamber is sealed. They turn on the measuring and recording equipment (3, 6, 7), turn on the valve control unit 8. On a signal from the control unit 8, the pump down valve 14 opens and the pressure in the working chamber 4 is abruptly (in a time of no more than 1 second) dropped to 0.4 kPa , which is noticeably lower than the pressure of saturated water vapor at room temperature, then, with the pump 15 running, in a time of no more than 10 seconds, it is reduced to 13 Pa. Intensive evaporation of moisture begins from the surface of the treated rock. The rock is kept under vacuum for 20 seconds. After that, the evacuation valve 14 is closed, and the inlet valve 13 is opened. Air inflow occurs in 20 seconds, the rock is kept for another 20 seconds at atmospheric pressure, then the inlet valve 13 closes (a full cycle, including pumping out and gas inflow, lasts 1 minute), then the full cycle is repeated the required number of times, until the rock freezes. Due to mechanical deformations of the rock, both during evacuation and when pressurizing, the rock disintegrates for conditions when the rock has not yet frozen. Freezing of rocks occurs due to the extraction of energy by evaporation of moisture. The temperature of the rock tends to an equilibrium value for saturated water vapor at a steady pressure in the chamber. The phase transition of the water contained in the clay to a frozen, solid state, accompanied by a decrease in density, which causes additional disintegration. The number of pumping-filling cycles is determined by the freezing of clay rock, which is controlled by the readings of temperature sensors 10, installed at different depths along the thickness of the rock. After the rock freezes, the heater 11 is turned on, which, within 10 minutes, leads to the rock thawing and the temperature rise to room temperature. After that, the vacuum cycle is repeated until the next freezing. The freezing-heating process is repeated until the amount of moisture becomes insufficient to freeze the rock. This is monitored by three 10 temperature sensors installed in different areas of the rock.

The use of the invention makes it possible to intensify the process and increase the efficiency of disintegration of gold-bearing clay rocks.

Claims (4)

1. A method of vacuum disintegration of gold-bearing clay rocks, including carrying out impulse high-speed vacuuming of no more than 1 s with a pressure in the working chamber of 0.4 kPa and a subsequent decrease to 13 Pa in a time of no more than 10 s with a working vacuum pump, characterized in that the clay the rock in the form of a flat layer 1-5 cm thick is placed in a working chamber in a clay rock pan with a built-in heater with an adjustable power up to 200 W, the rock is kept under the influence of vacuum for 20 s, then the atmosphere is puffed in for 20 s, the rock is kept at atmospheric pressure for 20 s, then the pumping-filling cycle is repeated until the rock freezes, which occurs during vacuuming due to the intense evaporation of moisture from the rock, after the rock freezes, a heater is turned on, which in 10 minutes leads to the rock thawing and the temperature rise to room temperature, at In this case, the freezing-heating process is repeated until the remaining amount water becomes insufficient to freeze the rock, while 2 to 10 pumping-inlet cycles are carried out. 2. A method according to claim 1, characterized in that for a clay layer thickness of 1 cm, 2 pumping-filling cycles are carried out. 3. The method according to claim 1, characterized in that for a clay layer thickness of 5 cm, 10 pumping-filling cycles are performed. 4. A device for vacuum disintegration of gold-bearing clay rocks, containing a working chamber and a receiver, the volume ratio of which is <1: 200, a vacuum pump with a capacity of ≥0.5 m ³ / s connected to the receiver, high-speed pneumatic valves for pumping out and filling the atmosphere, characterized in that the working chamber contains a sump for clay rock, which is equipped with a heater with an adjustable power up to 200 W and three temperature sensors, made with the possibility of installation at different depths in the thickness of the rock.

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