Gold ore in quartz primarily contains sulfur in sulfide minerals, with common sulfides including pyrite, chalcopyrite, bornite, and galena. These sulfides require oxidation treatment during the ore beneficiation process to oxidize the sulfides into sulfate ions or sulfuric acid, facilitating subsequent metal extraction processes. The following methods describe how sulfur in gold ore is treated with oxidation agents.
The peroxide oxidation method involves using peroxides to oxidize sulfur in gold ore into sulfate ions or sulfuric acid. This method is characterized by its simplicity of operation and fast reaction rate, making it one of the widely used oxidation treatment methods. The specific operational process is as follows:
Pre-treatment: After gold ore undergoes crushing, leaching, and other pre-treatment processes, a suitable slurry is obtained.
Oxidation Reaction: A suitable amount of peroxide is added to the slurry to oxidize the sulfides, generating sulfate ions or sulfuric acid.
Alkali Treatment: The oxidized slurry is subjected to alkali treatment to neutralize excess acid and adjust the pH of the slurry.
Precipitation Separation: The oxidized sulfate ions or sulfuric acid is separated from other substances using precipitation separation.
Filtration and Washing: The precipitate is filtered and washed to remove impurities.
Reduction Treatment: The oxidized slurry undergoes reduction treatment to reduce metal minerals.
The chlorination method involves using chlorine gas to oxidize sulfur in gold ore into chlorides, which are then hydrolyzed to form sulfuric acid. Although the chlorination method has a fast reaction rate, it requires complex operation and attention to safety. The specific operational process is as follows:
1.Slurry Pre-treatment
Gold ore needs to undergo pre-treatment, including crushing, leaching, and other processes. The obtained slurry must meet certain physical and chemical indicators, such as concentration and acidity.
2.Chlorine Gas Oxidation
Chlorine gas is introduced into the slurry, reacting to form chlorides. The chemical equation for chlorine gas oxidation reaction is:
FeS2 + 2Cl2 + 2H2O → FeCl2 + 2HCl + H2SO4
In this reaction, chlorine gas oxidizes sulfides, generating sulfuric acid and chlorides. The chlorides can be converted into sulfate ions or sulfuric acid through hydrolysis reactions.
3.Hydroxide Treatment
The oxidized slurry undergoes hydroxide treatment to convert the chlorides into sulfate ions or sulfuric acid. Sodium hydroxide or calcium hydroxide is commonly used, with the chemical equation as follows:
2FeCl2 + 2NaOH → Fe2O3 + 2NaCl + H2O
In this reaction, hydroxide reacts with chlorides to produce iron hydroxide and sodium chloride. Iron hydroxide can be converted into sulfate ions or sulfuric acid through hydrolysis reactions.
4.Hydrolysis Reaction
After hydroxide treatment, hydrolysis reactions are conducted to convert chlorides into sulfate ions or sulfuric acid. The chemical equation for hydrolysis reaction is:
2NaCl + H2O → Na2SO4 + 2HCl
In this reaction, sodium chloride reacts with water to produce sodium sulfate and hydrochloric acid. Sodium sulfate can be further processed to extract metals.
5.Precipitation Separation
After hydrolysis reactions, some precipitates and suspensions are formed. Precipitation separation is conducted to separate sulfate ions or sulfuric acid from other impurities.
