RU2246002C1 - Method for extracting gold from ores in place of deposition thereof - Google Patents

Abstract

FIELD: mining industry.

SUBSTANCE: method includes prior pumping into bed through system of feed wells of solution, containing sodium hypochlorite or chloride, draining product solutions through draining wells system. Fed solution additionally has hydrogen chloride with following ratio of components, g/l: sodium hypochlorite 0.4-1.0, sodium chloride 3.0-4.0, hydrogen chloride 0.3-1.0. sodium hypochlorite solution is received directly at place of use via electrolysis of sodium chloride solution. For receiving sodium hypochlorite solution rotation compounds are used, received after productive solutions cycle through absorption columns.

EFFECT: higher safety.

3 cl

Description

The invention relates to the mining industry, in particular to the technology of gold leaching, and can be used in underground and heap leaching of gold, as well as in hydrometallurgy in the extraction of precious metals from ores and concentrates.

There is a method of extracting gold from ores, including preliminary acidification of the ore with a solution of hydrochloric acid and leaching of ore with hydrochloric acid solutions containing halite and molecular chlorine [1].

The disadvantage of this method is the relatively low recovery of gold, the danger of transportation and storage of chlorine.

A known method of extracting gold from ores, including the preparation of a leaching solution of hydrochloric or other mineral acid, neutralized with an alkaline solution of sodium or potassium hypochlorite. Neutralization is carried out immediately before the acid solution is fed into the ore [2].

The disadvantage of this method is the insufficiently high recovery of gold, since in an alkaline environment gold is precipitated and partially sorbed onto clay minerals such as kaolinite, montmorillonite, halloysite present in the weathering crust, as well as a decrease in the rate of filtration of leaching solutions and even termination of the filtration process.

Closest to the proposed one is a method of extracting gold from ores at the place of their occurrence, which includes the sequential injection of solutions containing hypochlorite and sodium chloride into the formation through a system of injection wells, pumping of productive solutions through a system of pumping wells. The injected solution additionally contains sodium carbonate in the following ratio of components, g / l: sodium hypochlorite 0.5-1.5, sodium chloride 200-300, sodium carbonate 5-60, water the rest [3].

The disadvantage of the closest analogue is not high enough gold recovery, due to the low efficiency of the leaching solution.

The objective of the invention is to increase the extraction of gold.

EFFECT: elimination of the risk of emergencies with chemical reagents in the process of underground leaching.

The technical result is achieved by the fact that in the method for extracting gold from ores at the place of their occurrence, including sequential injection into the reservoir through a system of injection wells of a solution containing hypochlorite and sodium chloride, pumping productive solutions through a system of pumping wells, according to the invention, the injected solution additionally contains chloride hydrogen in the following ratio of components, g / l:

sodium hypochlorite 0.4-1.0

sodium chloride 3.0-4.0

hydrogen chloride 0.3-1.0

The sodium hypochlorite solution can be obtained directly at the place of its application by electrolysis of a sodium chloride solution.

To obtain a solution of sodium hypochlorite, you can use circulating solutions obtained after the passage of productive solutions through sorption columns.

The supply of hydrogen chloride - hydrochloric acid in an amount of 0.3-1.0 g / l allows you to maintain a solution pH of 2 to 4, which is necessary to prevent the deposition of gold and its partial sorption on clay minerals such as montmorillonite, kaolin, gallausite in the weathering crust, as well as to prevent the clogging of the filter zone of the injection wells and ditches.

Obtaining a solution of sodium hypochlorite directly at the place of its application by electrolysis, and as a result, having residual sodium chloride, contributes to a more efficient leaching of metals. Sodium chloride is present in the solution as residual after electrolysis. The initial solution for electrolysis is prepared from table salt of the brand “Technical rock salt, grade 1, grinding No. 2”, manufactured according to TU 9192-069-00209527-98. It is possible to use other grades of table salt, only the procedure for cleaning it from impurities changes.

The use of circulating solutions to obtain a solution of sodium hypochlorite contributes to a significant increase in the productivity of the electrolyzer; so when using an electrolyte prepared on the basis of industrial water, the duration of the electrolysis process is 70 minutes, and when preparing an electrolyte based on circulating solutions supplied by the pump from the settling tank after passing the productive solutions through the sorption columns, the process duration is reduced to 40 minutes.

The method is as follows.

The ore body to be mined is opened with a system of injection and observation wells, and filtration ditches. In the process of excavation of mine workings, samples are taken from them in order to clarify the material composition of the ore body and the host rocks, as well as the position of the zones of lowered and increased water conductivity. After the equipment of the underground leaching range is equipped with a piping system, acidic solutions containing sodium hypochlorite with a concentration of 0.4-1.0 g / l begin to be fed into the horizons, while the pH of the solution is maintained at a level of 2-4 by adding hydrochloric acid with a concentration of 0.3-1 , 0 g / l. The injection wells are located higher in the fall of the ore body and in such a way as to prevent the spreading of the solution beyond the boundary of the mined block.

Sodium hypochlorite is obtained directly at the place of its application by electrolysis of a solution of sodium chloride (sodium chloride), which greatly simplifies the storage and use of the reagents used, as well as their delivery to the place of work. The use of sodium chloride to produce sodium hypochlorite at the site of its use eliminates the risk of emergency situations with chemicals during underground leaching.

The use of circulating solutions for dissolving sodium chloride obtained after the passage of productive solutions through sorption columns significantly increases the performance of the electrolysis unit.

When using the finished sodium hypochlorite, delivered from chemical plants, sodium chloride with a concentration of from 3 to 12% is added to the leach solution.

In the working solution of sodium hypochlorite obtained by electrolysis at the place of its use, there is residual sodium chloride in an amount sufficient for the course of the leaching process.

Start mining the block in acidification mode, i.e. a solution containing a high concentration of hydrochloric acid (1 g / l) is fed into the wells with a normal sodium hypochlorite content (0.4 g / l), the pH of the supplied solution being 1.8-2.5. The solution is not pumped out for a period corresponding to the time of its spreading to the boundary of the block being worked out, then the pumping wells are turned on, a depression funnel is created and the balance of pumping - pumping of the solutions is regulated.

The rows of pumping and injection wells are positioned so that the solution flows naturally according to the fall of the ore body from the injection wells to the pumping wells, evenly working out the ore mass of the block being mined. The parameters of the stable chemical balance of the solutions are as follows: pH of the injection solution 2-3, ORP 1150-1250, pumped - pH 4-5, ORP 900-1000. The optimal solution filtration rate is determined on the basis of studies of the hydrogeological conditions of the field and can vary from 0.4 to 1 m / day, depending on the water conductivity of the rocks and the depth of the depression funnel.

To control possible leakages of productive solutions beyond the boundaries of the processed rock block, a number of observation holes are drilled around its perimeter, from which water samples are periodically taken for chemical analysis.

At the end of the leaching process, after the extraction of precious metals with sufficient completeness, groundwater is reclaimed. For this purpose, the supply of hypochlorite and hydrochloric acid to the horizon is stopped, but the circulation of solutions from the pumping wells through sorption columns continues, until the chlorine content reaches the background value for this site, the pH rises to the natural groundwater acidity in this field.

Sources of information

1. Nebera V.P. and others. "On the extraction of gold from the bowels by underground leaching." Gold hydrometallurgy, M., Nedra, 1980 p. 63-67.

2. RF patent No. 2094605, cl. E 21 B 43/28, publ. 10/27. 1997.

3. Copyright certificate of the USSR No. 1745906, class. E 21 B 43/28, publ. 07/07/1992.

Claims (3)

1. The method of extracting gold from ores at the place of their occurrence, including the sequential injection into the reservoir through a system of injection wells of a solution containing hypochlorite and sodium chloride, pumping productive solutions through a system of pumping wells, characterized in that the injection solution additionally contains hydrogen chloride in the following ratio components, g / l: Sodium hypochlorite 0.4-1.0 Sodium Chloride 3.0-4.0 Hydrogen chloride 0.3-1.0 2. The method according to claim 1, characterized in that the sodium hypochlorite solution is obtained directly at the place of its application by electrolysis of a sodium chloride solution. 3. The method according to claim 2, characterized in that to obtain a solution of sodium hypochlorite use circulating solutions obtained after the passage of productive solutions through sorption columns.