CN116287745A - A method for extracting silver from refractory silver-bearing rhodochrosite - Google Patents

Abstract

The invention provides a method for extracting silver from refractory silver-containing rhodochrosite, which comprises the following steps: crushing and finely grinding silver-containing rhodochrosite, and then carrying out ore phase reconstruction with acid and chloride auxiliary agents to obtain slurry 1; carrying out solid-liquid separation on the slurry 1 to obtain filtrate and residues; leaching the residue with a leaching agent to obtain slurry 2; carrying out solid-liquid separation on the slurry 2 to obtain a silver-containing leaching solution and leaching residues; and adding a reducing agent into the silver-containing leaching solution to carry out displacement reaction, so as to obtain silver concentrate containing metallic silver. The invention aims at destroying the crystal structure of the iron-manganese carbonate mineral by mineral phase reconstruction, exposing the wrapped silver, increasing the contact area with the leaching agent, promoting ion diffusion, finally realizing the efficient leaching of the silver and greatly improving the leaching rate of the silver.

Description

A method for extracting silver from refractory silver-bearing rhodochrosite

technical field

The invention relates to the technical field of mineral processing, in particular to a method for extracting silver from refractory silver-bearing rhodochrosite.

Background technique

Silver exists in a small amount in the form of elemental silver in nature, and a large amount is associated with other metal minerals in the form of compounds. The world's silver ore resources can be divided into two categories: one is an independent silver deposit with silver as the main mineral, accounting for about 1/3; the other is a total of copper, lead, zinc, gold and other non-ferrous and precious metal deposits ( Accompanied by) raw silver deposits, accounting for about 2/3. Among the sulfide minerals, silver is most commonly found in galena, chalcopyrite, and sphalerite. At present, about 25% of the world's annual output of silver mine products comes from silver mines, 15% from associated silver from gold mines, 24% from associated copper mines, 35% from lead, zinc and lead-zinc associated silver, and other ores Associated with 1% silver. my country's proven silver reserves account for 7.7% of the world's total, ranking fifth in the world. my country's co-genetic (associated) silver ore reserves account for 87% of the total reserves, and are the main body of silver ore resources, occupying a very important position in my country's silver ore resources. Therefore, carrying out research on the comprehensive utilization of co-generated (associated) silver ore resources plays a decisive role in improving my country's silver production and accelerating economic development.

The beneficiation methods of silver ore mainly include gravity separation and flotation process. China's independent silver mines that mainly produce silver basically use the flotation method, and the associated silver mines mostly use: single flotation method, flotation-gravity separation method, flotation-cyanide method combined process, of which flotation Choose the most important. The metallurgical extraction methods of silver mainly include hydrometallurgy and pyrometallurgy. The associated silver ore of lead-zinc-copper ore is generally sorted according to the process conditions and chemical system of its main metal. Usually, silver is enriched in lead, zinc, and copper concentrates, and then recovered through smelting. The beneficiation products of some independent silver mines and gold-silver co-(associated) mines recover silver through the wet cyanidation process, and some low-grade silver mines recover silver through the heap leaching process.

A silver-bearing rhodochrosite ore, the mineral composition is mainly rhodochrosite (siderosite), magnetite, quartz, ferrodolomite, garnet, etc., containing Ag 60-120g/t, and the silver minerals are mainly in the form of Micro-fine particles are embedded in iron-manganese carbonate minerals and quartz minerals in a disseminated state, and the silver minerals are fine and wrapped, using flotation-leaching, grinding-leaching, ultra-fine grinding-leaching, ultra-fine grinding-flotation- The leaching and other processes are used for silver-bearing rhodochrosite ore, and the Ag leaching rate is not more than 5%, and the ideal technical indicators have not been obtained.

Patent document-CN103773971B discloses a method for improving the silver leaching rate of polymetallic complex gold concentrate roasting-acid leaching-cyanidation process, the polymetallic complex gold concentrate is mixed with sodium hydroxide, roasted, and acid leached to obtain acid leaching slag, and then put the acid leaching residue in the acid fluoride salt system to strengthen the mineral phase reconstruction, and finally carry out cyanidation leaching. The roasting operation in this scheme is helpful to improve the silver leaching rate, but the Ag leaching rate is about 40%.

Contents of the invention

The invention proposes a method for extracting silver from refractory silver-bearing rhodochrosite, aiming at solving the problem of efficient separation and recycling of silver in the silver-bearing rhodochrosite.

The technical scheme of the present invention is achieved in that a kind of method for extracting silver from refractory silver-bearing rhodochrosite, comprises the following steps:

(1) crushing and finely grinding silver-containing rhodochrosite ore to obtain fine-grained minerals;

(2) Mineral phase reconstruction: stirring and reacting fine-grained minerals with acid and chloride salt additives to obtain slurry 1;

(3) Solid-liquid separation: the slurry 1 is subjected to solid-liquid separation and washed to obtain filtrate and residue;

(4) Silver leaching: the residue and the leaching agent are subjected to a leaching reaction to obtain a slurry 2 .

(5) Solid-liquid separation: the slurry 2 is subjected to solid-liquid separation and washed to obtain silver-containing leachate and leaching residue;

(6) Precipitation of silver: adding a reducing agent into the silver-containing leaching solution for reaction to obtain a silver concentrate containing metallic silver.

Further, in step (1), fine grinding to -0.045mm accounts for 60%-95%.

Further, in step (2), the acid is sulfuric acid or hydrochloric acid in an amount of 0.5-3mol/L; the auxiliary agent is NaCl in an amount of 0-2mol/L; reaction conditions: liquid-solid ratio 2:1-6:1, The temperature is 5°C-40°C, and the time is 0.5-8h.

Further, in step (4), lime is used to control the pH of the reaction solution at 11-12.5; the leaching agent is sodium cyanide, and the dosage is 0.5-8mol/L; reaction conditions: liquid-solid ratio 3:1-6:1, temperature 10°C-40°C, time 12-72h.

Further, in step (6), the reducing agent is zinc powder, and the amount of zinc powder is such that the molar ratio of Zn:Ag is 0.5-0.6:1.

Principle of the present invention is:

(1) Ore phase reconstruction: Rhodochrosite in the ore reacts chemically with acid to destroy the crystal structure of silver-containing iron-manganese carbonate minerals, so that the wrapped silver can be fully exposed and the subsequent silver leaching can be improved The contact area between the leaching agent and silver in the operation can realize the efficient cyanide leaching of silver, and the chemical reaction that occurs is shown in formula (1).

MnFe(CO ₃ ) ₂ + 2H ₂ SO ₄ ＝MnSO ₄ + FeSO ₄ + 2CO ₂ ↑+ 2H ₂ O (1)

The ore also contains a small amount of magnetite, iron dolomite, garnet and other minerals, and the following reactions may occur during the mineral phase reconstruction process:

Fe ₃ O ₄ + 4H ₂ SO ₄ ＝FeSO ₄ + Fe ₂ (SO ₄ ) ₃ + 4H ₂ O (2)

CaCO ₃ + H ₂ SO ₄ ＝CaSO ₄ + CO ₂ ↑+H ₂ O (3)

MgCO ₃ + H ₂ SO ₄ ＝MgSO ₄ + CO ₂ ↑+H ₂ O (4)

FeCO ₃ + H ₂ SO ₄ ＝FeSO ₄ + CO ₂ ↑+H ₂ O (5)

The role of additive Cl ^- (NaCl): in the sulfuric acid reaction system, Cl ^- consumes calcium carbonate and increases the solubility of calcium sulfate through the chemical reaction of hydrochloric acid, reduces the thickness of the CaSO ₄ coating on the mineral surface, and increases the specific surface area and pore volume of the leaching slag at the same time , destroy the structure of rhodochrosite minerals, promote ion diffusion, and finally promote the leaching of silver.

(2) Silver leaching: The exposed silver reacts with sodium cyanide to enter the solution, and the chemical reactions are shown in formulas (6) and (7).

2Ag+ 4NaCN+ O ₂ + 2H ₂ O = 2NaAg(CN) ₂ + 2NaOH+ H ₂ O ₂ (6)

2Ag+ 2NaCN+ H ₂ O ₂ ＝ 2NaAg(CN) ₂ + 2NaOH (7)

(3) Precipitation of silver: Zinc powder reacts chemically with silver leaching solution to obtain silver concentrate containing metallic silver. The chemical reaction is shown in formula (8).

2Ag ⁺ + Zn＝2Ag↓+ Zn ²⁺ (8)

Beneficial effects of the present invention:

The invention destroys the crystal structure of iron-manganese carbonate minerals through mineral phase reconstruction, and the silver distributed in the iron-manganese carbonate mineral lattice in the form of isomorphism and the silver distributed in the iron-manganese carbonate minerals in the form of fine particle inclusions The silver in salt minerals or micro-cracks can be exposed, which increases the contact area between the leaching agent and silver, increases the specific surface area and pore volume of the leaching slag, promotes ion diffusion, and finally realizes efficient cyanidation leaching of silver, greatly improving the leaching of silver. Cyanide leaching rate. Tests have shown that the direct cyanide leaching rate of the silver-containing rhodochrosite silver is 2-5%, which belongs to typical refractory silver ores, and is difficult to develop and form economic benefits. And finally, the leaching rate of silver can be increased to more than 90%.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a flow chart of a method for extracting silver from refractory silver-bearing rhodochrosite of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

As shown in Figure 1, a kind of method of extracting silver from refractory smelting silver-bearing rhodochrosite, comprises the following steps:

(1) Sample preparation: crush and finely grind the ore containing Ag 60.53g/t to obtain -0.045mm fine-grained minerals accounting for 60%;

(2) Ore phase reconstruction: react fine-grained minerals with 0.5mol/L sulfuric acid at a liquid-solid ratio of 2:1 and a temperature of 5°C for 0.5h to obtain slurry 1;

(3) Solid-liquid separation: the slurry 1 is subjected to solid-liquid separation, and washed 2-3 times to obtain filtrate and residue;

(4) Silver leaching: use lime to pretreat the residue, control the pH of the solution to 11, add 0.5mol/L sodium cyanide, and react for 12 hours at a liquid-solid ratio of 3:1 and a temperature of 10°C to obtain a slurry 2.

(5) Solid-liquid separation: the slurry 2 is subjected to solid-liquid separation, and washed 2-3 times to obtain silver-containing leachate and leaching residue;

(6) Precipitation of silver: Add zinc powder to the silver-containing leaching solution for reaction to obtain silver concentrate containing metallic silver. The amount of zinc powder is Zn:Ag molar ratio of 0.6:1.

In the final test, the leaching rate of Ag was 80.59%.

Example 2:

As shown in Figure 1, a kind of method of extracting silver from refractory smelting silver-bearing rhodochrosite, comprises the following steps:

(1) Sample preparation: crush and finely grind the ore containing Ag 65.85g/t to obtain -0.045mm fine-grained minerals accounting for 85%;

(2) Ore phase reconstruction: react fine-grained minerals with 2mol/L sulfuric acid and 1mol/L NaCl at a liquid-solid ratio of 4:1 and a temperature of 25°C for 4 hours to obtain slurry 1;

(3) Solid-liquid separation: the slurry 1 is subjected to solid-liquid separation, and washed 2-3 times to obtain filtrate and residue;

(4) Silver leaching: use lime to pretreat the residue, control the pH of the solution to 11.5, add 3mol/L sodium cyanide, and react for 48 hours at a liquid-solid ratio of 4:1 and a temperature of 25°C to obtain slurry 2 .

(5) Solid-liquid separation: the slurry 2 is subjected to solid-liquid separation, and washed 2-3 times to obtain silver-containing leachate and leaching residue;

(6) Precipitation of silver: Add zinc powder to the silver-containing leaching solution for reaction to obtain silver concentrate containing metallic silver. The amount of zinc powder is Zn:Ag molar ratio of 0.6:1.

In the final test, the leaching rate of Ag was 88.72%.

Example 3:

As shown in Figure 1, a kind of method of extracting silver from refractory smelting silver-bearing rhodochrosite, comprises the following steps:

(1) Sample preparation: crush and finely grind the ore containing Ag 90.20g/t to obtain -0.045mm fine-grained minerals accounting for 95%;

(2) Ore phase reconstruction: react fine-grained minerals with 3mol/L sulfuric acid and 2mol/LNaCl at a liquid-solid ratio of 6:1 and a temperature of 40°C for 8 hours to obtain slurry 1;

(3) Solid-liquid separation: the slurry 1 is subjected to solid-liquid separation, and washed 2-3 times to obtain filtrate and residue;

(4) Silver leaching: use lime to pretreat the residue, control the pH of the solution to 12.5, add 8mol/L sodium cyanide, and react for 72 hours at a liquid-solid ratio of 6:1 and a temperature of 10°C to obtain slurry 2 .

(5) Solid-liquid separation: the slurry 2 is subjected to solid-liquid separation, and washed 2-3 times to obtain silver-containing leachate and leaching residue;

(6) Precipitation of silver: Add zinc powder to silver-containing leaching solution for reaction to obtain silver concentrate containing metallic silver. The amount of zinc powder used is Zn:Ag molar ratio of 0.55:1.

In the final test, the leaching rate of Ag was 93.57%.

Example 4:

As shown in Figure 1, a kind of method of extracting silver from refractory smelting silver-bearing rhodochrosite, comprises the following steps:

(1) Sample preparation: crush and finely grind the ore containing Ag 120g/t to obtain -0.045mm fine-grained minerals accounting for 90%;

(2) Mineral phase reconstruction: react fine-grained minerals with 2.5mol/L sulfuric acid and 1.5mol/LNaCl at a liquid-solid ratio of 5:1 and a temperature of 35°C for 6 hours to obtain slurry 1;

(3) Solid-liquid separation: the slurry 1 is subjected to solid-liquid separation, and washed 2-3 times to obtain filtrate and residue;

(4) Silver leaching: use lime to pretreat the residue, control the pH of the solution to 12, add 6mol/L sodium cyanide, and react for 48 hours at a liquid-solid ratio of 5:1 and a temperature of 35°C to obtain slurry 2 .

(5) Solid-liquid separation: the slurry 2 is subjected to solid-liquid separation, and washed 2-3 times to obtain silver-containing leachate and leaching residue;

(6) Precipitation of silver: Add zinc powder to silver-containing leaching solution for reaction to obtain silver concentrate containing metallic silver. The amount of zinc powder used is Zn:Ag molar ratio of 0.55:1.

In the final test, the leaching rate of Ag was 92.34%.

Example 5:

As shown in Figure 1, a kind of method of extracting silver from refractory smelting silver-bearing rhodochrosite, comprises the following steps:

(1) Sample preparation: The ore containing Ag 93g/t is crushed and finely ground to obtain -0.045mm fine-grained minerals accounting for 92%;

(2) Ore phase reconstruction: react fine-grained minerals with 2mol/L sulfuric acid and 1mol/L NaCl at a liquid-solid ratio of 4:1 and a temperature of 30°C for 5 hours to obtain slurry 1;

(3) Solid-liquid separation: the slurry 1 is subjected to solid-liquid separation, and washed 2-3 times to obtain filtrate and residue;

(4) Silver leaching: use lime to pretreat the residue, control the pH of the solution to 11.5, add 6mol/L sodium cyanide, and react for 60 hours at a liquid-solid ratio of 4:1 and a temperature of 30°C to obtain slurry 2 .

(5) Solid-liquid separation: the slurry 2 is subjected to solid-liquid separation, and washed 2-3 times to obtain silver-containing leachate and leaching residue;

(6) Precipitation of silver: Add zinc powder to the silver-containing leaching solution for reaction to obtain silver concentrate containing metallic silver. The amount of zinc powder is Zn:Ag molar ratio of 0.6:1.

In the final test, the leaching rate of Ag was 91.66%.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (5)

1. a method for extracting silver from refractory silver-bearing rhodochrosite, is characterized in that, comprises the following steps: (1) crushing and finely grinding silver-containing rhodochrosite ore to obtain fine-grained minerals; (2) Mineral phase reconstruction: stirring and reacting fine-grained minerals with acid and chloride salt additives to obtain slurry 1; (3) Solid-liquid separation: the slurry 1 is subjected to solid-liquid separation and washed to obtain filtrate and residue; (4) Silver leaching: the residue and the leaching agent are subjected to a leaching reaction to obtain a slurry 2 . (5) Solid-liquid separation: the slurry 2 is subjected to solid-liquid separation and washed to obtain silver-containing leachate and leaching residue; (6) Precipitation of silver: adding a reducing agent into the silver-containing leaching solution to carry out a replacement reaction to obtain a silver concentrate containing metallic silver. 2. A method for extracting silver from refractory silver-bearing rhodochrosite according to claim 1, characterized in that, in step (1), fine grinding to -0.045mm accounts for 60%-95%. 3. a kind of method for extracting silver from refractory silver-bearing rhodochrosite according to claim 1, is characterized in that, in step (2), acid is sulfuric acid or hydrochloric acid, and consumption is 0.5-3mol/L ; The chlorine salt additive is NaCl, and the dosage is 0-2mol/L; Reaction conditions: liquid-solid ratio 2:1-6:1, temperature 5°C-40°C, time 0.5-8h. 4. a kind of method for extracting silver from refractory smelting silver-containing rhodochrosite according to claim 1, is characterized in that, in step (4), adopt lime to control reaction solution pH at 11-12.5; Leaching agent It is sodium cyanide, the dosage is 0.5-8mol/L; reaction conditions: liquid-solid ratio 3:1-6:1, temperature 10°C-40°C, time 12-72h. 5. A method of extracting silver from refractory silver-containing rhodochrosite according to claim 1, characterized in that, in step (6), the reducing agent is zinc powder, and the Zn:Ag mol ratio is 0.5 -0.6:1.

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