Fused magnesia-calcium sand technology and its application status

The current sintering flue gas desulfurization technologies for fused magnesia-calcium sand mainly include limestone/lime-gypsum method, dual-alkali method, desulfurized magnesium oxide, ammonia-ammonium sulfate method, etc. Agricultural magnesium oxide

1. Limestone/lime-gypsum method and application

The limestone/lime-gypsum method is the earliest SO2 removal technology in industrial application. This method uses limestone or lime slurry as desulfurization agent, and reacts with SO2 in flue gas in the form of spraying in the absorption tower for desulfurization. The reaction product is by-product gypsum. The process flow is shown in Figure 1. Initially, the CaSO4·2H2O produced during the operation process is very low in solubility and precipitates out, which is easy to cause fouling and blockage of the equipment and affect the operation of the system. Later, by supplying gypsum seeds to the system to control the supersaturation of gypsum in the system slurry, the scaling and clogging problems were basically solved. Calcined Dolomite

2. Double alkali method and its application

The operation process of the double-alkali method is divided into absorption, regeneration and solid separation. It was originally developed by the United States and Japan for the easy scaling and clogging of the limestone/lime-gypsum method. There are sodium-calcium double-alkali method, calcium-calcium method, alkaline Aluminum sulfate-gypsum method, ammonia-gypsum method, etc. At present, the sodium-calcium double-alkali method is used more, that is, sodium-alkali (Na2CO3/NaOH) is used in the absorption tower to absorb SO2, and calcium-alkali [Ca(OH)2] is used outside the tower to regenerate and recycle NaOH. high. This method is suitable for the treatment of flue gas with high SO2 concentration, and the desulfurization rate is high, but the power consumption is large. The 2×24m2 sintering machine of Guangzhou Iron and Steel Co., Ltd. of my country adopts the dual-alkali method independently developed by my country, and the desulfurization efficiency is over 84%, which meets the requirements of environmental protection.

Agricultural magnesium oxide

3. Magnesium oxide method and application

Desulfurization of magnesium oxide uses MgO as a desulfurizer, and the MgO raw material is made into Mg(OH) 2 slurry and reacts with SO2 in the flue gas, mainly producing Mg2SO3 and other products. If MgSO3 is forcibly oxidized to form MgSO4, the by-product after separation and drying is solid MgSO4. If the oxidation is suppressed, MgSO3 is not oxidized to form MgSO4, and the final product is Mg2SO3, which is separated, dried, roasted, and finally reduced to magnesium oxide and SO2 gas with a certain concentration. After reduction, magnesium oxide is returned to the system for reuse, and SO2 gas is used for Make sulfuric acid. Calcined dolomite roasting MgSO3 needs to control the temperature, the system is quite complicated, and the investment cost is high. The current magnesium oxide desulfurization method mostly adopts the method of generating MgSO4 as the final product. The current sintering flue gas desulfurization technologies for fused magnesia-calcium sand mainly include limestone/lime-gypsum method, dual-alkali method, desulfurized magnesium oxide, ammonia-ammonium sulfate method, etc.