News Date:2020-10-10
1. The necessity of steel slag pretreatment process
Steel slag is the impurities discharged from steel making process, complex material chemical reaction in the process of steelmaking slag products and various materials and other materials together to form. The main components of steel slag are composed of calcium silicate minerals, metal iron and iron oxides. Calcium silicate minerals and other components is mainly composed of two calcium silicate (2CaO - SiO2), three calcium silicate (3CaO - SiO2), olivine (CaO - RO - SiO2), Rhodonite (3CaO RO 2SiO2) and RO phase (solid solution MgO, MnO, FeO).
The iron in steel slag is mainly composed of MFe, FeO and Fe2O3. The metal iron is about 10% and the iron oxide is about 20%. Metal, iron and iron oxides in steel slag can be recycled as iron resources. Calcium silicate minerals can be used in construction and other fields. It should be said that steel slag has the material base as a resource. China has a large population, and will still be in a large-scale infrastructure construction in recent years. Although the production capacity is surplus, the resources are still very poor in itself. However, the preparation of iron and cement and other raw materials, high energy consumption, large amount of gas emissions, the effective utilization of steel slag resources is of great significance.
At present, the process of steel slag treatment in China mainly includes hot compaction, hot splashing and rotary drum method. Among them, hot compaction and hot splashing process are most popular. The selection of steel slag pretreatment process depends on two factors, namely, the resource flow direction of slag and its own nature. At present, the resource flow of steel slag mainly consists of two aspects: the recovery of iron from steel slag, and the usage of tailings in the materials for construction, road and other fields. Therefore, first of all, to achieve the efficient separation of the two types of materials, we can use them separately.
The steel slag processing mainly uses water as a medium for cooling treatment on the steel slag, through physical cooling to achieve the separation of materials containing iron and calcium silicate in steel slag, so that crushing and magnetic separation can be conducted to effectively facilitate the separation of the two kinds of material. The iron containing material obtained by crushing and magnetic separation can be returned to act as raw material for the production of iron and steel, and tailings act as inorganic materials and are applied to construction, roads and other fields.
Whether it is used as building material or road steel slag, steel slag is often required to have good stability and lower metal iron content, so as to prevent safety and quality problems in the use of steel slag. Because the slag contains certain free calcium magnesium oxide, the calcium magnesium oxide expands with water, which brings the safety problem of steel slag as building material. Therefore, the steel slag is required to be stabilized during the pretreatment process to eliminate the free calcium and magnesium oxides, so as to ensure the stability of the steel slag used as a building, road and other steel slag products.
Make a summary that, steel slag must be pretreated before application, in order to achieve the physical separation of materials containing iron and silicate, while achieving stabilization of steel slag, for buildings, roads and other areas.
2. Main slag pretreatment process
The most primitive treatment process for steel slag is the waste slag disposal process, that is, pour the slag slag into the slag pot (or slag tank) and after cooling, transport the slag to the slag storage field or discard it. In the past, steel mills all over the world mainly adopted this method. With the increasing emphasis on the utilization of solid waste and the development of corresponding technologies, the treatment process of steel slag is also changing with each passing day.
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