The adsorption capacity of natural bentonite is poor. In order to improve its adsorption capacity, it must be activated to meet the requirements of food, chemical industry, environmental protection, petroleum and other application fields. The activated bentonite is called activated clay, and its color is gray white, pink or white.

① Raw material preparation: dry the bentonite (generally calcium based bentonite) until the water content is less than 15%, remove the stone inclusions, and crush it to 100~200 meshes. The weathered bentonite does not need to be crushed. If the sand content is large, remove the sand particles.

② Acidification: usually active with hydrochloric acid or sulfuric acid, or organic acid. For bentonite containing calcite, hydrochloric acid is preferred. A certain amount of acid is added into the bentonite slurry, heated and stirred for a certain time. The main factors affecting the activation effect are acid dosage, slurry concentration, activation time, temperature and stirring conditions. The amount of acid is generally about 300-600kg/100kg bentonite; The water/soil ratio is generally 0.8~1:1, and the activation temperature is 50~100 ℃; The reaction time depends on the operating conditions, generally 2~8h; Continuous stirring is required for activation

③ Washing: After activation, wash repeatedly until the washing solution is neutral. Due to the fine particle size of bentonite, it is not easy to settle. In order to accelerate the settlement, an appropriate amount of efficient flocculant can be added.

④ Filtration: use pressure filtration or vacuum suction filtration process to remove most of the water in the washed active clay slurry

⑤ Drying: It is generally required that the moisture content of the dried product is less than 8%

⑥ Grinding: generally, active clay Raymond mill is used to grind the dried active clay to 200 meshes

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