RU2811646C1 - Method for extracting gold from solutions by sorption on active carbon - Google Patents

Abstract

FIELD: hydrometallurgy of precious metals.

SUBSTANCE: invention relates to the extraction of gold from solutions or pulps by coal sorption. The method includes countercurrent movement of active carbon and solution flow through sorption columns. The loading of active carbon in each sorption column is uneven - from smaller to larger towards the flow of the solution.

EFFECT: increase in the capacity of the sorbent for a useful component with a total comparable extraction of gold from solutions.

1 cl, 1 tbl, 2 ex

Description

The invention relates to the hydrometallurgy of precious metals, in particular to the extraction of gold from solutions by sorption onto active carbon.

There are known methods for extracting noble metals by sorption from solutions in a chain of sorption columns (CIC). The number of sorption columns is from 3 to 6. The solution flow moves through the column from bottom to top through the sorbent layer. Gold is deposited along the height of the column on active carbon. After the coal is saturated, one or two columns are removed from the deposition chain and transferred to the cycle for removing gold from coal. The loading of coal into the sorption columns is uniform. [M.I. Fizlullin, 2001. “Heap leaching of noble metals.” 251 pages].

The disadvantages of this method include the relatively small capacity of the saturated sorbent, which leads to an increased flow of saturated sorbent for desorption and regeneration of the sorbent, an increase in capital and operating costs at this stage. And also the impossibility of carrying out sorption and desorption operations on pulps, due to unsatisfactory filtration of the pulp through a layer of coal.

There are known methods for extracting noble metals by sorption from pulps (CIP or CIL) or solutions (CIC) in a cascade of sorption columns. The number of sorption stages is 3-5 from solutions. The number of sorption stages is 5 - 10 from pulps. The flow of pulp or solution moves towards the flow of the sorbent. Coal periodically moves from column to column, towards the flow of pulp or solution. Saturated coal is unloaded from the first column, regenerated sorbent is loaded into the last column. The loading of coal into the sorption columns is uniform. [I.N. Maslenitsky, L.V. Chugaev, “Metallurgy of Precious Metals”, 1987, pp. 238-240].

The disadvantages of this method include the relatively small capacity of the saturated sorbent, which leads to an increased flow of saturated sorbent for desorption and regeneration of the sorbent, which increases capital and operating costs at this stage.

Methods for extracting noble metals by sorption from pulps (CIP or CIL) or solutions (CIC) in a cascade of sorption columns are also known. The number of sorption stages is 3-5. The flow of pulp or solution moves towards the flow of the sorbent. Coal periodically moves from column to column, towards the flow of pulp or solution. Saturated coal is unloaded from the first column, regenerated sorbent is loaded into the last column. The loading of coal into the sorption columns is uniform. [M.A. Meretukov, “Activated carbons and the cyanide process,” 2007, pp. 227-228, 241-242, 248-249].

The disadvantages of this method include the relatively small capacity of the saturated sorbent, which leads to an increased flow of saturated sorbent for desorption and regeneration of the sorbent, with a subsequent increase in capital and operating costs at this stage.

The objective of the invention is to increase the capacity of gold-saturated coal to improve the quality of the resulting “commercial” eluates and, as a consequence, to improve the quality of the cathode deposit obtained during further electrolytic deposition of gold from the eluates. Reducing the flow of saturated sorbent to the stages of desorption of gold from coal, regeneration of the sorbent, reducing capital and operating costs at these stages.

The technical result is achieved by the fact that in the proposed method, the loading of coal into the sorption columns is uneven - from less to more towards the flow of the solution. Thus, the ratio of the gold flow to the mass of coal per unit time in the sorption column is slightly greater than in the classical version, all other things being equal.

The compliance of the claimed invention with the requirement of inventive step is determined by the fact that its distinctive feature is the uneven loading of coal in the sorption columns, which makes it possible to increase the gold capacity of activated carbon due to a slightly larger ratio of the gold flow to the mass of coal in the sorption column per unit time.

The above is confirmed, but is not limited to examples of implementation of the proposed method.

Example 1 (based on the prototype).

Activated carbon, with a total mass of 12.5 g, was evenly distributed over a cascade of four sorption columns, 3.125 g in each column. At a given flow rate of 0.1 l/hour, a gold-containing cyanide solution was supplied to the cascade of sorption columns. The gold concentration in the feed to the cascade of sorption columns was 1 mg/l. The coal in the sorption columns worked in a “fluidized bed”. Gold from the solution was sorbed onto coal. The solution was deashed, the coal was saturated with gold. During the testing process, the supply of solution, the concentration of gold in the feed and the tailings of the cascade of sorption columns were monitored every 4 hours. After each sorption column, the gold concentration was controlled in a steady state, after the coal was saturated and the gold concentration in the tailings increased to more than 0.04 mg/l. At the end of the tests, coal from each sorption column, a cascade of sorption columns, was analyzed for gold content to compare and analyze the operation of a branch of sorption columns. The concentration of gold in the tailings of the cascade of sorption columns was 0.05 mg/l. Gold recovery from coal was 95%. The capacity of saturated coal in the first sorption column was 1.53 mg/g. The sorption productivity for coal was 1.56 g/day.

Example 2 (according to the proposed method).

Activated carbon, with a total mass of 12.5 g, was unevenly distributed over a cascade of four sorption columns - 2.00 g in the first column, 3.00 in the second column, 3.50 in the third column, 4.0 in the fourth sorption column. At a given flow rate of 0.1 l/hour, a gold-containing cyanide solution was supplied to the cascade of sorption columns. The gold concentration in the feed to the cascade of sorption columns was 1 mg/l. The coal in the sorption columns worked in a “fluidized bed”. Gold from the solution was sorbed onto coal. The solution was deashed, the coal was saturated with gold. During testing, the supply of solution, the concentration of gold in the feed and the tails of the cascade of sorption columns were monitored every 4 hours. After each sorption column, the gold concentration was controlled in a steady state, after the coal was saturated and the gold concentration in the tailings increased to more than 0.04 mg/l. At the end of the tests, coal from each column of the cascade of sorption columns was analyzed for gold content to compare and analyze the performance of the branch of sorption columns. The gold concentration in the tailings of the cascade of sorption columns was 0.04 mg/l. Gold recovery from coal was 96%. The capacity of saturated coal in the first sorption column was 2.08 mg/g. The sorption productivity for coal was 1.15 g/day.

Table 1 presents the parameters and indicators of the compared methods.

It has been experimentally established that uneven loading of active carbon into sorption columns - from less to more towards the flow of the solution - can significantly increase the capacity of the saturated sorbent sent for subsequent desorption of gold.

Thus, the use of the proposed method of sorption of gold from solutions makes it possible to increase the capacity of the sorbent for the useful component by 26.4%.

In turn, the optimal amounts of coal loading into sorption columns will depend on the initial concentration of gold in the liquid phase and the flow of solution entering sorption in each specific case.

Claims (1)

A method for extracting gold from solutions by sorption onto activated carbon, including countercurrent movement of active carbon and solution flow through sorption columns, characterized in that the loading of active carbon in each sorption column is uneven - from less to more towards the solution flow.