The process comprises the following steps: preparation of a mixed system of sodium iodate, sodium iodide and water; production of complex salts of Au(I) and Au(I₃) under the action of the as-prepared mixed solution and a co-oxidant; extraction of crude gold powder; and purification to obtain refined gold powder.

Compared with the prior art, the gold iodide leaching method adopted in this process significantly improves the extraction recovery and purity of the recovered gold. Meanwhile, the process features simple operation, low environmental risk of the involved chemicals, and low cost, thus reducing production cost and improving production efficiency. Furthermore, iodine can be recycled and reused in the process, which further cuts production costs.

The lead-bearing gold concentrates are treated with the independently developed crystallization washing technology, which enables hydrometallurgical separation of impurities including lead, iron and sulfur during gold smelting and extraction. This process features innovative and unique design, strong adaptability, and wide applicability for refining lead-bearing concentrates (including middlings) obtained from Knelson gravity concentration. It also provides high reference value for the processing of other lead-bearing concentrates.

An increasing number of domestic gold mining enterprises in China have adopted the Knelson gravity concentration process. At present, most Knelson gravity concentrates are processed via pyrometallurgical smelting, which is associated with harsh working conditions and high risk of lead poisoning. The application of this new process can thoroughly address the lead pollution problem, thus filling the domestic gap in this technical field.

Process for Comprehensive Recovery of Precious and Rare Metals (Gold, Silver, Platinum and Palladium) from Gold-Bearing Waste

This process is implemented as follows:

Gold-bearing waste is first roasted in a rotary kiln, after which copper, bismuth and other impurities are leached out using sulfuric acid, industrial salt and sodium chlorate. Copper and bismuth in the primary leachate are recovered separately with caustic soda and soda ash.

The primary leaching residue is then leached with hydrochloric acid (or sulfuric acid) and sodium chlorate to obtain secondary leaching residue and a gold-, platinum- and palladium-bearing solution. Silver remains in the secondary leaching residue and is enriched therein.

After the pH of the gold-, platinum- and palladium-bearing solution is adjusted by adding soda ash, anhydrous sodium sulfite is dosed into the solution. Precipitation and filtration are then carried out to produce sponge gold and a platinum- and palladium-bearing solution.

Zinc powder is added to the platinum- and palladium-bearing solution, and platinum-palladium sludge and wastewater are obtained after further precipitation and filtration. Palladium powder and platinum powder are finally produced via conventional platinum and palladium extraction processes.

The present invention can address the common defects of traditional processes, including severe environmental pollution, low direct recovery rate, slow capital turnover and low labor productivity.

The specific process is as follows: First, crush and grind the gold-bearing waste into powder, then dissolve the powder in aqua regia solution. Next, add an alkaline solution to neutralize the pH of the mixed system, and filter out the precipitates. Add ATRZ solution to the obtained clear and transparent solution containing chloroaurate ions. After stirring, collect the produced solid precipitate through filtration, wash it with water and dry it to obtain an intermediate product. 

Add water to the intermediate product, heat the mixture under stirring, then add concentrated hydrochloric acid dropwise for reaction to finally obtain elemental gold. This method has the advantages of simple operation, rapid extraction process and extremely high extraction efficiency.

Beneficiation Method for High-Oxidation-Rate Complex Copper Ore Containing Paragenetic and Associated Metals:

This method comprises the following steps: grinding the run-of-mine ore and conditioning it into Pulp 1; subjecting Pulp 1 to copper sulfide flotation to obtain Copper Sulfide Concentrate 1, copper sulfide middlings and copper sulfide tailings; subjecting the copper sulfide tailings to copper oxide flotation to obtain Copper Oxide Concentrate 1, copper oxide middlings and copper oxide tailings; and separately cleaning the copper sulfide middlings and copper oxide middlings to obtain Copper Sulfide Concentrate 2 and Copper Oxide Concentrate 2 respectively.

Through separate treatment of the middlings, both high-grade and low-grade copper sulfide concentrates, as well as high-grade and low-grade copper oxide concentrates, are produced. By sorting the high-grade and low-grade copper sulfide and copper oxide concentrates, the subsequent metallurgical process flowsheet is simplified, copper recovery is improved, the recovery of paragenetic and associated metal resources (especially precious metals) is enhanced, production costs are reduced, and economic benefits are boosted.

Gold-silver alloys can be separated via chemical methods and electrolytic methods. Chemical methods include the chlorination process, nitric acid decomposition process and sulfuric acid decomposition process.

(1) The chlorination process is based on the difference in chemical affinity between different metals and chlorine. It selectively chlorinates impurity metals respectively, and separates gold, silver and impurities by controlling the temperature within an appropriate range, leveraging the different melting and boiling points of various metal chlorides. Although simple to operate, this method causes environmental pollution and yields gold and silver with low purity, so it is rarely applied in industrial production.

(2) The nitric acid decomposition process separates gold-silver alloys based on the principle that under the action of concentrated nitric acid, silver and other heavy metal impurities dissolve in nitric acid, while only gold remains insoluble. This method has drawbacks including high cost of nitric acid and environmental pollution, making it unsuitable for large-scale application.

(3) The sulfuric acid decomposition process achieves the separation of gold, silver and other impurities based on the principle that silver and other impurity elements in gold-silver alloys are readily soluble in hot concentrated sulfuric acid, whereas gold is insoluble.

(4) The electrolytic method is carried out in two steps: In the first step, the alloy is used as the anode for electrolysis, where electrolytic silver is obtained at the cathode, and gold is enriched in the anode slime (a standard term for by-products of electrolytic refining in metallurgy). In the second step, the anode slime is melted and cast into an anode for secondary electrolysis, and electrolytic gold is obtained at the cathode.

The specific steps are as follows:

a. Gold ore pretreatment: Remove impurities such as clay and silt from the surface of the mined gold ore, then crush and screen the ore. Select ore fractions with a particle size of less than 70 mm, mix them with slaked lime at a specified proportion, and stir thoroughly to obtain a mixture, which is then piled up to form an ore heap.

b. Preparation of infiltration agent: Adjust the pH of the solvent to 10-12 to obtain an alkaline solution, and add sodium cyanide to prepare the infiltration agent.

c. Spraying: Spray the infiltration agent onto the ore heap continuously to collect the pregnant solution (gold-bearing leachate).

d. Collection of gold-loaded carbon: Pump the pregnant solution into an adsorption column packed with activated carbon. The gold-bearing complexes in the pregnant solution are adsorbed by the activated carbon, yielding gold-loaded carbon and barren solution with low gold content. The barren solution is recycled and treated before being reused in steps b, c and d.

e. Extraction of elemental gold: The gold-loaded carbon obtained in step d is processed to extract elemental gold.

The flotation-acid leaching process for complex low-grade copper oxide ores comprises the following steps:

The raw low-grade copper oxide ore is crushed, ground, and prepared into ore pulp;

Flotation reagents are added to the above ore pulp, and one stage of roughing and one stage of scavenging are conducted to obtain copper oxide concentrate and tailings;

The obtained copper oxide concentrate is prepared into ore pulp, then concentrated sulfuric acid is added for leaching under agitation. Solid-liquid separation is performed afterwards to produce copper-bearing leachate and leaching residue.

This process integrates flotation and acid leaching to treat low-grade copper oxide ores. The low-grade copper oxide ore is subjected to one-stage roughing and one-stage scavenging flotation in the presence of a sulfidizing agent, which realizes the preliminary separation of high acid-consuming silicate and carbonate minerals (including chlorite, dolomite, talc, etc.) from copper sulfide minerals in the ore. Combined with the subsequent acid leaching process, copper leaching can be achieved at a relatively low acid consumption. This process overcomes the defects of existing technologies for copper enrichment from low-grade copper oxide ores, such as complex process flow, high reagent consumption and high production cost.

The beneficiation method for gold ore comprises the following steps: classify gold-bearing minerals to obtain a coarse fraction and a fine fraction; sequentially subject the coarse fraction to sluice rougher separation and shaking table cleaning separation to obtain Concentrate A; process the fine fraction via flotation to obtain Concentrate B, and mix Concentrate A and Concentrate B to produce gold concentrate.

The collector used in the flotation process consists of the following components in parts by mass: 25-35 parts of mercaptobenzothiazole, 5-10 parts of ammonium dibutyl dithiophosphate, 3-5 parts of soluble alkali, 0.3-1 part of fatty alcohol polyoxyethylene ether, and 55-60 parts of solvent.

By adopting the gravity-flotation combined process flow for ore treatment, this method recovers coarse-grained gold through gravity separation, and recovers fine-grained and micro-fine-grained gold through flotation. It effectively addresses the difficulties in beneficiation and recovery of gold with different grain sizes (coarse, fine and micro-fine), realizes highly efficient recovery of gold minerals, and delivers a relatively high gold recovery rate.