Bauxite Ore Extraction Process

Bauxite Ore Extraction Process

Bauxite is main material in aluminium making. Silica is main detrimental impurities in alumina making. Bauxite ores has many uses and the most important one is that bauxite is used as metal aluminium refining and refractory material and abrasive materials and high aluminium cement material in aluminum industry.Bauxite processing is relatively simple and hand dressing is used commonly. The design is that: washing for three times, crushing for two times and hand dressing for one time. Along with the development of refractory material and alumina industry in our country, the production of bauxite raw materials is put forward higher and higher demand.

Bauxite Ore processing flowchart

For bauxite is regarded as smelting aluminium material, different smelting methods have different quality demands. The ratio of SiO2/Al2O3 is more than 8 ~ 10 in bayer process, 5~7 in combined process and 3.5~5.0 in sintering process. Therefore as smelting aluminium material, the primary task in bauxite dressing is to improve the ratio of SiO2/Al2O3. At the same time, iron oxide in ores will reduce productivity of dissolution kettle in bayer process and reduce clinker temperature in sintering process and prevent alumina from becoming sodium aluminate. At present, after the raw ore is fine ground, then through desilicication flotation, high gradient strong magnetic deironing and corresponding measures to removing impurities such as potassium and sodium, inferior bauxite will become bauxite with good quality.

Sintering process

This method is suitable for treating low grade ores with high silicon content. It requires that the Al2O3/SiO2 is 3~5(3.5 or so) and the Fe2O3 content is below 10%. In modern industry, the sintering process is alkali-lime sintering process. The bauxite is mixed with certain soda ash and lime (or limestone). Then through high temperature sintering, oxidation silicon and lime synthesize original calcium silicate that is insoluble in water and iron oxide synthesizes iron acid sodium which is easily hydrolyzed. Alumina and soda ash can synthesize sodium metaaluminate that is water soluble. When the sintering products clinker is leached out, sodium metaaluminate comes into solution so that it can seperate from original calcium silicate and hydrate ferric oxide.