Magnesium slag is the solid waste discharged from the magnesium metal plant during the magnesium smelting process. The process of producing metal magnesium is roughly as follows: dolomite is calcined in a rotary kiln, then ground into powder, mixed with ferrosilicon powder and fluorite powder, made into balls, and sent into a heat-resistant steel reduction tank. Coarse magnesium is produced by reduction at a temperature of 190-1210°C and a vacuum of ~10 Pa, and then through flux refining, ingot casting, and surface treatment, metal magnesium ingots are obtained, and the remaining residue is magnesium slag. How to make full use of magnesium slag has become a major theme restricting the development of magnesium industry. As a manufacturer of magnesium slag grinding mill, today Guilin Hongcheng will discuss with you the comprehensive utilization of magnesium slag.
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The main components of magnesium slag are CaO, SiO2, and unreduced MgO. Due to the differences in production conditions and processes of various magnesium plants, the composition of magnesium slag is not fixed, but has a fluctuation range. The fluctuation range of magnesium slag composition: CaO is 40%~50%; SiO2 is 20%~30%; A12O3 is 2%~5%; MgO is 6%~10%; Fe2O3 is about 9%. According to its composition, the comprehensive utilization of magnesium slag can consider several directions:
1. Using magnesium slag to make new wall materials
It has been reported that the magnesium slag is directly mixed with the finely ground slag according to a certain ratio, and the compound activator is added to prepare the cementing material. Studies have shown that the process of using magnesium slag to produce wall materials is simple, low-cost, and energy-saving, and the cementitious material produced by this metal magnesium slag has good gelling properties, and the wall material made of it has low density and high strength. High, durable, product quality in line with relevant standards. Most enterprises only use magnesia slag to make bricks. In fact, they can also mix a certain amount of lightweight aggregate into magnesia slag to make lightweight heat-insulating and heat-insulating wall materials or roofing materials.
2. Use metal magnesium slag to make mineralizer
Magnesium slag is a new type of mineralizer developed in recent years. After being calcined at a high temperature of about 1200°C, the magnesium slag has certain chemical activity, which can reduce the nucleation potential energy of crystals, induce crystals, accelerate the transformation and formation of minerals, and reduce Heat loss from raw meal to clinker. Therefore, it is possible to try burning raw meal with different ratios of magnesium slag, and study the formula with higher tensile and compressive strength of clinker. Studies have shown that adding about 10% magnesium slag to the raw meal can have a good mineralization effect during calcination. The price of magnesium slag and fluorite is very different. It is very significant to use magnesium slag instead of part of fluorite as mineralizer to reduce production cost and improve economic benefits.
3. Production of construction cement using magnesium slag
Magnesium slag can replace part of slag to produce mixed cement admixture, and the quality of the produced cement is relatively stable. However, with the increase of magnesium slag content, the early strength of cement tends to decrease and the setting time prolongs. Therefore, when magnesium slag is used as admixture in cement production, it should meet the relevant technical requirements of national standards.
4. Production of masonry cement
Masonry cement is a hydraulic cementitious material made of one or more active mixed materials or hydraulic industrial waste as the main raw material, adding an appropriate amount of Portland cement clinker and gypsum, and grinding. This kind of cement has low strength and cannot be used for reinforced concrete or structural concrete. It is mainly used for masonry, plastering mortar, cushion concrete, etc. in industrial and civil buildings. Studies have shown that the activity of magnesium slag is higher than that of slag, and its grindability is better than that of slag and clinker. Using magnesium smelting waste slag to produce masonry cement can significantly improve the activity of cement, increase output, and reduce energy consumption for cement production.
5. Production of composite Portland cement
Composite Portland cement is a hydraulic cementitious material made of Portland cement clinker, two or more specified mixed materials, and an appropriate amount of gypsum. It is called composite Portland cement. The total amount of mixed materials in the cement should be greater than 20% by mass percentage and not more than 50%. The principle of using magnesium slag to produce composite Portland cement is to add magnesium smelting waste slag to the cement raw material, and after calcining it into Portland cement clinker, then add an appropriate amount of magnesium slag and other admixtures, and grind it to obtain composite cement (MgO mass Fraction approx. %). It should be noted that when magnesium slag is used to produce composite Portland cement, the dosage range should meet the limit requirements of periclase content in cement.
6. Use magnesium slag as desulfurizer
Since the desulfurization technology of circulating fluidized bed boiler mainly uses calcium oxide for desulfurization, and the mass fraction of calcium oxide in magnesium slag is about 50%, so it is meaningful to study the desulfurization performance of magnesium slag. The desulfurization effect is mainly related to the particle size, porosity, desulfurization temperature and other factors of magnesium slag. Magnesium slag with smaller particle size and higher porosity can improve the desulfurization efficiency of magnesium slag under appropriate air excess coefficient and temperature.
7. Magnesium slag as road material
Magnesium slag can be used as a good road material because the content of calcium and magnesium in magnesium slag is very high, and it has relatively high activity. It reacts with soil in the base layer to form insoluble hydrous calcium silicate and hydrous calcium aluminate, which are in a gel state. Or fibrous crystals, which strengthen the connection and cohesion between the mixture particles. With the growth of age, these hydrates increase day by day, so that the base layer of magnesium slag mixture can obtain greater and greater resistance to load.
The comprehensive utilization of magnesium slag needs to go through the grinding process. Therefore, the magnesium slag grinding mill has become an ideal equipment to help the treatment and utilization of magnesium slag. The Raymond mill and vertical grinding mill produced by Guilin Hongcheng can process 80-600 mesh magnesium slag powder according to the needs of magnesium slag treatment. If you have a magnesium slag comprehensive utilization project, please leave us a message for equipment details.
