With the continuous development of economic globalization, competition in the steel active lime market is becoming increasingly fierce. Traditional slag-making raw materials such as silicate or fluorite are used in the steelmaking process, and their effects can no longer meet the needs of the steel market. In order to speed up the slag formation in the steelmaking process, active lime is used in steelmaking. The chemical properties of active lime and its ability to participate in the reaction are very strong, and the content of harmful impurities is small. Therefore, active lime is used in steelmaking. Active lime
1. Overview of Active Lime
Due to its high reactivity, active lime can be quickly and completely miscible with molten steel in a short time. During the steelmaking process, the molten steel and different substances react to produce harmful substances, namely, steel slag. In order to ensure the quality of steel, slag removal is required. Adding limestone to molten steel as a slag-forming agent has a significantly higher effect than silicate or fluorite. However, it also has a drawback. Limestone is prone to endothermic reactions, that is, calcium carbonate decomposition reactions, and requires a large amount of heat, and slag formation is delayed. And because the molten steel cools quickly, the calcium carbonate decomposition reaction not only absorbs a large amount of heat, but also delays the slagging time, so that when the slagging starts, the heat shortage occurs. This not only prolongs the steelmaking time, but also increases the consumption of raw materials, and the quality of slag making will also decrease. Therefore, it is proposed that limestone be calcined first and then used in steelmaking.
Lime powder can also be called calcium carbonate. Calcium carbonate active lime manufacturers are a very common mineral in our lives. It is mainly the main component of limestone and calcite. The use of this mineral for limestone has a long history. White powdery substance with calcium carbonate as the main component. The application range is very wide, the most common is used in the construction industry, that is, industrial calcium carbonate; the other is food-grade calcium carbonate, as a common calcium supplement, is widely used. There are two types of calcium supplements commonly used in calcium supplements: one is heavy calcium carbonate, which is limestone that is crushed to a certain fineness for use as a food additive; the other is light calcium carbonate, which is calcined by limestone Got.
(1) Determination of lime activity by acid-base titration.
(2) Lime activity index
An index to characterize the hydration reaction speed of quicklime, that is, in a sufficient time, it is expressed by the number of milliliters of 4mol / L hydrochloric acid consumed by neutralizing Ca (OH) 2 produced during quicklime digestion.
(3) Definition of lime activity: The structure of lime is closely related to the calcination temperature and calcination time. Microstructures that affect lime activity include bulk density, porosity, specific surface area, and grain size of CaO minerals. The smaller the grains, the larger the specific surface area, the higher the porosity, the higher the lime activity and the stronger the chemical reaction ability. (4) Application: Steelmaking practice shows that the price of this active lime can increase the dephosphorization and desulfurization efficiency by 80%, and at the same time shorten the smelting time. It can completely react with the acidic materials in the molten steel within 3-5min. The response time should be at least 6-10min. In addition, the furnace age is increased by more than 40%, and the consumption of furnace charge is also reduced by 5-8kg / t steel. Based on 10 million tons, it saves about 15 million per year and has significant production benefits.