The Production of Coal and Slag Superfine Powder

Slag and fly ash is a by-product of industrial waste residue. Nowadays, the domestic industrial waste or by-product species emissions can be divided into some kinds: slag, coal powder, steel slag, zeolite powder and silica fume. Silica fume is suitable for high-performance concrete production, but it is so expensive and rare that it cannot meet the requirement of mass production. Slag and coal powder is rich and cheap, so they are widely applied.

The most important character of industrial slag and coal superfine powder is its raw material and fineness. The main chemical composition of coal superfine powder is SiO2, Al2O3 and Fe2O3. High-calcium fly ash includes much CaO whose application in concrete can improve its fluidity and reduce water consumption, thus improve its performance. Slag is the water quenching slag discharged from blast furnace, and its main composition is SiO2, Al2O3 and CaO, similar to cement. The materials are mainly 5μm to 10μm, which can improve its hydration activity.

1.The Production of Coal Superfine Powder:

The main equipment to classify coal superfine powder in electricity industry is classifier. Commercial coal powder production in construction industry often adopts open circuit grinding process or closed circuit grinding process of vertical mill. There is already some qualified coal powder in raw material. If we adopt the open circuit grinding process, over grinding will happen. In addition, it will bring low system productivity and high electricity consumption. With the development of classifying technology and equipment, the closed circuit grinding process can get higher system productivity. Compared with the cement closed circuit production process, the coal powder should be classified first before entering into mill. The coarse powder will enter into vertical mill to be grinded again, which can play the classifier's role fully and improve grinding productivity.

2. The Production of Slag Superfine Powder:

In our country, we mainly adopt vertical mill and ball mill to produce superfine slag. Vertical mill can finish grinding, classifying and drying work in mill at the same time. It is simple in operation, high in thermal efficiency, low in electricity consumption and regulatable in fineness. Ball mill is low in productivity and high in electricity. The discharging temperature is high and fineness regulation is troublesome.