Hexavalent chromium mainly comes from: chromium ore smelting, refractory materials, electroplating, tanning, pigments and chemical industries, as well as chromium-containing waste gas, waste water and waste residues discharged from fuel combustion. Hexavalent chromium cannot be decomposed in nature, pollutes soil and groundwater, is easily absorbed by the human body, and can accumulate in the body through digestion, respiratory tract, skin and mucous membranes. Therefore, the pollution of hexavalent chromium has attracted worldwide attention.

At present, there are four main sources of hexavalent chromium in cement: raw fuel, crushing and grinding equipment, magnesia-chrome brick, and industrial waste residue. Among them, the impact of raw materials and crushing equipment is relatively low, and the industrial waste residue containing chromium is easy to control. Therefore, the refractory material containing chromium in the firing system has become the main pollution source of hexavalent chromium in cement.

Through a recent survey, it was found that compared with ten years ago, there are not many domestic enterprises producing magnesia-chrome bricks. According to the statistics of Refractory Window, the enterprises still producing magnesia-chrome bricks are mainly concentrated in Liaoning and Henan provinces.

More companies are also undergoing transformation. Through technological innovation, refractory enterprises and scientific research units have strengthened the research and development of chromium-free refractories and accelerated the research and development of environmentally friendly refractories to meet the new requirements of the country for environmental protection. At the same time, it is also reducing the cost of materials, making it superior to the existing magnesia-chrome bricks in terms of performance and use cost, and replacing magnesia-chrome bricks by market means.

At present, the products that replace magnesia-chrome bricks mainly include magnesia-iron spinel bricks, magnesia-alumina spinel bricks, magnesia-zirconium bricks, dolomite bricks and other chrome-free refractories.