CGA production process starts from bauxite ore mining which is conducted by PT ANTAM Tbk’s West Kalimantan Bauxite Mining Business Unit. Bauxite production originated from Tayan bauxite mine in West Kalimantan. The mined bauxite is fed for consumption at the Tayan CGA plant in Tayan, West Kalimantan. The mine is conducted with open pit methods with truck and excavator. After the ore is mined, the ore is washed and screened to be transported to the Tayan CGA plant, which is located next to the mine.
In general, the term CGA refers to chemical products in the form of aluminium hydroxide and alumina used for various industrial applications except for aluminium industry. Aluminium hydroxide is a semi-finished product that can be used for water purification. While alumina can be used to produce electronic support components. Some products that use CGA include refractoriness, abrasive, assembled products, integrated circuit (IC), as well as basic materials for LCD screens. Alumina processing in Tayan will produce chemical grade alumina products by processing bauxite ore through the Bayer process into alumina products with a nameplate capacity of 300,000 metric tons of Al2O3 (alumina) base per year. The Bayer process consists of three stages, namely Liquor Clarification process, Precipitation Process, and Calcination Process.
Liquor clarification process begins with the grinding of bauxite ore by using rod mill to produce fine bauxite ore. The results of the rod mill will be mixed with a caustic soda solution that has been heated. The mixing process between the caustic soda solutions with fine bauxite ore is carried out in a pressure vessel. The result for this process is caustic soda solution enriched by dissolved alumina.
After the caustic soda and bauxite solutions react in the pressure vessel, then continued with the process of decreasing the temperature and the separation of the solution which is enriched by alumina and undissolved solid (red mud) using thickener. Red mud produced will be filtered while the solution enriched by alumina is filtered by diastar filter. The next step is the process of precipitation or recrystallization. In the main material process at ICA, this precipitation process is divided into 4 chain lines.
Calcination process is the heating treatment at high temperature below melting point which results in a phase change from aluminium hydrate (Al (OH)3) to alumina (Al2O3) and decomposition of crystal water (H2O). Eleven alumina products can be produced in rotary kilns with different calcination treatments.
The calcination process in the rotary kiln uses high speed diesel fuel (HSD) which is atomized using pressured air. After the calcining process, the alumina is cooled in the planetary cooler that rotates following the rotation of the kiln. After the cooling process, alumina products are accommodated in silos using air-based transport instruments. This aluminium will be further processed in the alumina processing process or directly sold depending on consumer demand. This calcination process is the end of the Bayer process.
The product of the Bayer process consists of two products, namely alumina trihydrate and alumina. Alumina trihydrate will be processed in the path of hydrate processing. The hydrate processing will proceed postproduction aluminium trihydrate from the hydrate production process by using various processes to meet product specification by performing size changes as well as other treatments such as coating and de-ionizing. The result of processing of alumina trihydrate will be packed in jumbo bag and paper bag ready to be sent to the consumer.
The alumina product which is the process of calcination will be processed further to meet the specifications of consumers. This further process involves mixing and filtering of the alumina blending. Alumina that has been in blending, will be packed or given further treatment. Then, the result of the processing of alumina will be packaged to be sent to the consumer.