CN102041393A - Silver anode mud treatment process - Google Patents

Abstract

The invention relates to a silver anode mud treatment process. The process is characterized by leaching silver anode mud with nitric acid, wherein silver, palladium and base metals enter into solution while gold and platinum remain in residue; after roasting the leaching residue and removing impurities, using a cast gold anode plate to electrolyze the leaching residue to obtain gold No. 1 and using electrolyte for recycling platinum; regulating the pH value of leachate and adding mixed precipitator A solution to selectively precipitate palladium to obtain palladium precipitate residues; solution after palladium precipitation mainly being AgNO3 solution and returning the AgNO3 solution to undergo silver electrolysis; dissolving the palladium precipitate residues with aqua regia and filtering the dissolved solution to obtain the filter residue which is mainly AgCl, reducing the filter residue with hydrazine hydrate to obtain crude silver powder and returning the crude silver powder to a cast silver anode plate; and concentrating and carrying out ammonium on the solution after dissolution to obtain (NH4)2PdCl6 precipitate, dissolving the (NH4)2PdCl6 precipitate with ammonia and acidizing the (NH4)2PdCl6 precipitate with hydrochloric acid to obtain Pd(NH3)2Cl2 precipitate, then reducing the Pd(NH3)2Cl2 precipitate with hydrazine hydrate and then drying the reduction product to obtain spongy palladium, wherein the produced filtrate is returned to the concentration process. The invention has the advantages of less precious metal loss, low cost, strong practicability, high comprehensive recoverability and obvious economic benefit.

Description

The treatment process of silver anode slime

Technical field

The present invention relates to a kind of treatment process of silver anode slime, belong to non-ferrous metal hydrometallurgy field.

Background technology

Electrolytic refining process is the common method of preparation high pure metal.As the electrorefining process of silver, be to make anode with thick silver, the titanium plate is made negative electrode, and silver nitrate aqueous solution is made electrolytic solution, at volts DS 1.5～3.5V, electric current 250～300A/m ²Condition under refining can obtain 99.99% silver.

Thick silver generally all contains plurality of impurities such as Au, Pt, Pd and base metal Pb, Cu, Bi before electrolysis.In electrolytic process, gold that electropotential ratio silver is big and platinum metals major part can not dissolved and be precipitated, and the base metal impurity part meeting that electropotential is littler than silver forms oxide compound or subsalt also can precipitate, and these throw outs have just constituted silver anode slime.The productive rate of silver anode slime is higher, is about 8%, and composition is more complicated also, and main chemical compositions is Au 30～40%, Ag40～50%, Pd1～2%, Pt 0.1～0.4%, Pb0.04～0.07%, Cu3～4%, Bi0.05～0.1%.So silver anode slime is the main raw material that extracts gold and reclaim the platinum palladium.

At present, silver anode slime usually adopts chlorination process to handle in large-lot producer, leaches with hydrochloric acid and sodium chlorate, silver-coloredly enters in the parting slag with AgCl, and parting liquid is with oxalic acid or SO ₂Reduction obtains thick bronze, carries out golden electrolysis then, reduction back liquid displacement platinum palladium.But problems such as there is the difficult control of leaching condition in this method, leaches reagent price height, precious metal is difficult to separate with base metal, platinum palladium separation difficulty, the rate of recovery are low.And this method is difficult to miniaturization, and the silver anode slime limited amount of general smelting enterprise can't be handled with aforesaid method, have to sell outward, is worth but precious metal so wherein is not recovered utilization and has a greatly reduced quality, and has caused enterprise's tremendous economic loss.Therefore be badly in need of a kind of novel process of invention and come the Processing Ag anode sludge.

Summary of the invention

In order to overcome the deficiency of above-mentioned silver anode slime treatment process, the invention provides a kind of treatment process of silver anode slime.This technology leaching condition is easy to control, make become separating of precious metal and base metal easily, the rate of recovery is high, and can miniaturization, be applicable to generally, or small-sized smelting enterprise comes the Processing Ag anode sludge.

The technical solution used in the present invention is: a kind of treatment process of silver anode slime, silver anode slime is leached with nitric acid, and the nitric acid leaching condition is a liquid-solid ratio 2～4: 1, nitric acid liquid concentration 20%～30%, 50～70 ℃ of temperature of reaction; Silver, palladium and base metal enter solution, and gold and platinum are stayed in the slag, separate after filtration leached mud and leach liquor; Casting Jinyang pole plate carries out electrolysis after the leached mud roasting removal of impurities, obtains the 1# gold; Electrolytic solution reclaims platinum and handles; Regulate the pH 0.5～2.5 of leach liquor, the mixed precipitant A solution that adds 1～1.4 times of theoretical amount precipitates palladium-selective, and 70～90 ℃ of temperature of reaction obtain heavy palladium slag; Liquid is mainly AgNO behind the heavy palladium ₃Solution returns silver-colored electrolysis treatment; Heavy palladium slag aqua regia dissolution after-filtration, filter residue are mainly the AgCl precipitation, obtain thick silver powder with hydrazine hydrate reduction, return the coin silver positive plate; Liquid concentrated also " ammoniumization " obtains (NH behind the aqua regia dissolution ₄) ₂PdCl ₆Precipitation; (NH ₄) ₂PdCl ₆Precipitation obtains Pd (NH behind ammonia dissolving, hcl acidifying ₃) ₂Cl ₂Precipitation obtains purity at the palladium sponge more than 99.9% again after hydrazine hydrate reduction, oven dry; Wherein the filtrate that Chan Shengs is returned concentration process; Above-mentioned ammonia dissolution conditions is 50～70 ℃ of temperature, terminal point pH8～9; Above-mentioned hcl acidifying condition is terminal point pH0.5～1.0.

Above-mentioned mixed precipitant A is a kind of xanthate solution, the chemical name of xanthate is alkyl xanthogenate or alkyl dithiocarbonate, general formula: ROC (S) SMe, and Me is sodium or potassium in the general formula, also have and make ammonium salt, R is different alkyl, alkaryl, cycloalkyl, alkoxyl group etc.The kind of xanthate is a lot, and commonly used have ethyl xanthate, butyl xanthate, sec.-propyl xanthate, Isobutylxanthic acid, amyl group xanthate, a hexyl xanthate etc.Xanthate energy and many heavy metals, precious metal ion generates insoluble chemical compound, as palladium of the present invention.

Compare with prior art, the present invention has following advantage:

The present invention sends out process can carry out selective separation with gold and silver platinum palladium, and can realize well that open circuit reclaims, and this processing to silver anode slime plays crucial effects.The present invention can carry out also can all carrying out in the part in actual applications, is applicable to the enterprise of various different scales.The advantage that this technology is outstanding is that the precious metal loss is little, cost is low, practical, comprehensively reclaim the degree height, economic benefit is obvious.

Description of drawings

Fig. 1 is a process flow sheet of the present invention.

Embodiment

Describe the present invention below in conjunction with accompanying drawing in detail with embodiment:

Embodiment 1

A kind of treatment process of silver anode slime leaches with 20% nitric acid liquid (liquid-solid ratio 2: 1) silver anode slime 50 ℃ of following mechanical stirring, silver, palladium and base metal enter solution, and gold and platinum are stayed in the slag.Casting Jinyang pole plate carries out electrolysis after the leached mud roasting removal of impurities, obtains the 1# gold, the recyclable platinum of electrolytic solution.Regulate leach liquor pH to 0.5, the mixed precipitant A solution that adds 1 times of theoretical amount precipitates palladium-selective under 70 ℃, obtains heavy palladium slag; Liquid is mainly AgNO behind the heavy palladium ₃Solution returns silver-colored electrolysis.Heavy palladium slag dissolves after-filtration fully with chloroazotic acid, and filter residue is mainly the AgCl precipitation, obtains thick silver powder with hydrazine hydrate reduction, returns the coin silver positive plate; Acid solution behind the aqua regia dissolution is boiled, be concentrated into about 1/5 of original volume, in solution, slowly add NH then ₄Cl obtains (NH ₄) ₂PdCl ₆Precipitation.(NH ₄) ₂PdCl ₆Be deposited in 50 ℃ and stir down, slowly add ammoniacal liquor until the pH to 8 of solution resolution of precipitate, continue solution is heated to boiling, be cooled to the room temperature after-filtration, in filtrate, slowly add hydrochloric acid to pH0.5, leave standstill for some time after-filtration and obtain Pd (NH ₃) ₂Cl ₂Precipitation obtains palladium sponge again after hydrazine hydrate reduction, oven dry, wherein the filtrate that Chan Shengs is returned concentration process.Gained palladium sponge purity is 99.91%, gold recovery 91.6%, silver raising recovery rate 95.3%, the platinum rate of recovery 92.3%, palladium recovery rate 94.2%.

Embodiment 2

A kind of treatment process of silver anode slime leaches with 25% nitric acid liquid (liquid-solid ratio 3: 1) silver anode slime 60 ℃ of following mechanical stirring, silver, palladium and base metal enter solution, and gold and platinum are stayed in the slag.Casting Jinyang pole plate carries out electrolysis after the leached mud roasting removal of impurities, obtains the 1# gold, the recyclable platinum of electrolytic solution.Regulate leach liquor pH to 1.5, the mixed precipitant A solution that adds 1.2 times of theoretical amount precipitates palladium-selective under 80 ℃, obtains heavy palladium slag; Liquid is mainly AgNO behind the heavy palladium ₃Solution returns silver-colored electrolysis.Heavy palladium slag dissolves after-filtration fully with chloroazotic acid, and filter residue is mainly the AgCl precipitation, obtains thick silver powder with hydrazine hydrate reduction, returns the coin silver positive plate; Acid solution behind the aqua regia dissolution is boiled, be concentrated into about 1/5 of original volume, in solution, slowly add NH then ₄Cl obtains (NH ₄) ₂PdCl ₆Precipitation.(NH ₄) ₂PdCl ₆Be deposited in 60 ℃ and stir down, slowly add ammoniacal liquor until the pH to 8.5 of solution resolution of precipitate, continue solution is heated to boiling, be cooled to the room temperature after-filtration, in filtrate, slowly add hydrochloric acid to pH0.8, leave standstill for some time after-filtration and obtain Pd (NH ₃) ₂Cl ₂Precipitation obtains palladium sponge again after hydrazine hydrate reduction, oven dry, wherein the filtrate that Chan Shengs is returned concentration process.Gained palladium sponge purity is 99.93%, gold recovery 91.8%, silver raising recovery rate 95.5%, the platinum rate of recovery 92.4%, palladium recovery rate 94.6%.

Embodiment 3

A kind of treatment process of silver anode slime leaches with 30% nitric acid liquid (liquid-solid ratio 4: 1) silver anode slime 70 ℃ of following mechanical stirring, silver, palladium and base metal enter solution, and gold and platinum are stayed in the slag.Casting Jinyang pole plate carries out electrolysis after the leached mud roasting removal of impurities, obtains the 1# gold, the recyclable platinum of electrolytic solution.Regulate leach liquor pH to 2.5, the mixed precipitant A solution that adds 1.4 times of theoretical amount precipitates palladium-selective under 90 ℃, obtains heavy palladium slag; Liquid is mainly AgNO behind the heavy palladium ₃Solution returns silver-colored electrolysis.Heavy palladium slag dissolves after-filtration fully with chloroazotic acid, and filter residue is mainly the AgCl precipitation, obtains thick silver powder with hydrazine hydrate reduction, returns the coin silver positive plate; Acid solution behind the aqua regia dissolution is boiled, be concentrated into about 1/5 of original volume, in solution, slowly add NH then ₄Cl obtains (NH ₄) ₂PdCl ₆Precipitation.(NH ₄) ₂PdCl ₆Be deposited in 70 ℃ and stir down, slowly add ammoniacal liquor until the pH to 9 of solution resolution of precipitate, continue solution is heated to boiling, be cooled to the room temperature after-filtration, in filtrate, slowly add hydrochloric acid to pH 1, leave standstill for some time after-filtration and obtain Pd (NH ₃) ₂Cl ₂Precipitation obtains palladium sponge again after hydrazine hydrate reduction, oven dry, wherein the filtrate that Chan Shengs is returned concentration process.Gained palladium sponge purity is 99.95%, gold recovery 92.1%, silver raising recovery rate 95.8%, the platinum rate of recovery 92.6%, palladium recovery rate 94.8%.

Claims (1)

1. the treatment process of a silver anode slime is characterized in that silver anode slime is leached with nitric acid, and the nitric acid leaching condition is a liquid-solid ratio 2～4: 1, nitric acid liquid concentration 20%～30%, 50～70 ℃ of temperature of reaction; Silver, palladium and base metal enter solution, and gold and platinum are stayed in the slag, separate after filtration leached mud and leach liquor; Casting Jinyang pole plate carries out electrolysis after the leached mud roasting removal of impurities, obtains the 1# gold; Electrolytic solution reclaims platinum and handles; Regulate the pH 0.5～2.5 of leach liquor, the mixed precipitant A solution that adds 1～1.4 times of theoretical amount precipitates palladium-selective, and 70～90 ℃ of temperature of reaction obtain heavy palladium slag; Liquid is mainly AgNO behind the heavy palladium ₃Solution returns silver-colored electrolysis treatment; Heavy palladium slag aqua regia dissolution after-filtration, filter residue are mainly the AgCl precipitation, obtain thick silver powder with hydrazine hydrate reduction, return the coin silver positive plate; Liquid concentrated also " ammoniumization " obtains (NH behind the aqua regia dissolution ₄) ₂PdCl ₆Precipitation; (NH ₄) ₂PdCl ₆Precipitation obtains Pd (NH behind ammonia dissolving, hcl acidifying ₃) ₂Cl ₂Precipitation obtains purity at the palladium sponge more than 99.9% again after hydrazine hydrate reduction, oven dry; Wherein the filtrate that Chan Shengs is returned concentration process; Above-mentioned ammonia dissolution conditions is 50～70 ℃ of temperature, terminal point pH8～9; Above-mentioned hcl acidifying condition is terminal point pH0.5～1.0.