The roasting of copper concentrate is to convert the sulfide minerals into oxidized minerals, so as to separate the useful components from the sulfur and iron, and realize their extraction. The roasted copper concentrate is basically a process of oxidation and sulfidation roasting.
At present, the most common method of copper concentrate smelting is sulfation roasting. Sulfation roasting has the advantages of simple operation, convenient control, low energy consumption and high production efficiency. The roasted copper concentrate generally needs to be pretreated before smelting to remove sulfur and iron impurities in the copper soluble copper ore. When the sulphur-containing impurity content is greater than 1%, it is necessary to complete the sulphur removal before the copper concentrate roasting process.
The sulphur removal process of roasted copper concentrate is mainly divided into two steps: physical removal and chemical separation. Physical removal is the use of high speed rotation or paddle-type agitator to stir the copper concentrate and then impregnate the flotation reagent to separate the copper concentrate from the gangue minerals. Chemical separation is mainly two methods: oxidation-sulfidation method and basic oxide method. The oxidation-sulfidation method is to reduce the sulfur content of the copper concentrate by adding sodium hydroxide and ferric sulfate and regulating the pH value. The basic oxide method is to reduce the sulfur content of the copper concentrate by adding sodium carbonate and calcium oxide, and adjusting the basic oxygen potential.
The roasting of copper concentrate is the oxidation of sulfide minerals and the production of sulfur dioxide. This process requires a high temperature and needs to use a roasting furnace, a gas-generating furnace and other auxiliary equipment. The roasting of copper concentrate is mainly divided into three steps: preheating, oxidation and sulfidation, and cooling.
Preheating is to raise the temperature of the copper concentrate to about 300°C in advance. The purpose of preheating is to reduce the roasting temperature of the concentrate, reduce the residence time of the oxidation and sulfidation reaction and save fuel. Oxidation-sulfidation is the main step in the roasting process. In this step, sulfur dioxide is generated by oxidation-sulfidation reaction, and the oxidation of copper concentrate is completed. Since the temperature at this time is relatively high, care must be taken to prevent the oxidative reaction from being too vigorous, which will lead to the overburn of copper concentrate. Finally, the cooling step is mainly to reduce the temperature of the roasted copper concentrate and prevent the re-oxidation of the roasted copper concentrate.
In summary, the roasting of copper concentrate is a complex technological process. In this process, attention should be paid to the detection and control of temperature, oxygen content, stirring speed, pulp concentration and reaction rate, so as to ensure the roasting quality of the roasted copper concentrate.
