Producing low-carbon pressed bricks
A new 15,000t production line that manufactures pressed bricks containing little or no embedded carbon has been developed by Gengsheng Minerals, based in Gongyi, China. The company creates bricks to be used in furnaces and ladles for iron and steel mills.
Raw bauxite, silica powder or brown fused alumina are ground together and the mix is treated with chemical compounds to create a chemical reaction. The mixture is then poured into the pressing machine, where 70t of pressure is applied to form the brick shapes. These are then fired in a kiln at 1,700ºC.
‘We use proprietary technologies during mixing and wet treatment,’ explains Valentine Ding, Spokesperson for Gengsheng. ‘By optimising the ingredients and the chemical reaction, we can determine the carbon content of the finished product.’
The resulting bricks contain either no carbon, or carbon in concentrations of five per cent or less. They have been successfully tested for refractory applications by holding molten steel heated to 1,600ºC for three hours, without eroding.
Ding says the bricks can be mass-manufactured in different shapes and sizes, depending on customer needs, although production times are longer than for normal pressed bricks. ‘It will take around 22 days to produce 100t of bricks – 10 days to build the mould, two days for mixing the raw materials, seven days for pressing/forming, and three days for firing.’
The product is also twice as expensive as Gengsheng’s unshaped refractory products, but are a popular option for those who seek to manufacture steel in a low carbon furnace. The company has already received contracts from some of China’s largest steel makers, such as Baosteel and Angang steel.