Fly Ash Grinding Mills
Fly ash is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases. Ash which does not rise is termed bottom ash. In an industrial context, fly ash usually refers to ash produced during combustion of coal. Fly ash is generally captured from the chimneys of coal-fired power plants, and together with bottom ash removed from the bottom of the furnace is in this case jointly known as coal ash. Depending upon the source and makeup of the coal being burned, the components of fly ash vary considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO2) (both amorphous and crystalline) and calcium oxide (CaO), both being endemic ingredients in many coal-bearing rock strata. In the past, fly ash was generally released into the atmosphere, but pollution control equipment mandated in recent decades now require that it be captured prior to release. In the US, fly ash is generally stored at coal power plants or placed in landfills. About 43 percent is recycled, often used to supplement Portland cement in concrete production. Some have expressed health concerns about this.
Fly Ash Mill
Fly ash is one of largest emissions of the industrial waste residues in current China. Nowadays, the yearly industrial slags have reached 30 million tons, and with the development of power industry, the emissions of fly ash from coal-fired power factories will increase year by year. A large number of unprocessed fly ash will generate dust and pollute the atmosphere; if discharged into the water system, the fly ash can cause the rivers blockage and the toxic chemicals contained in it will be harmful to the human body and life-forms.
Therefore, based on based on conserving resources and reducing pollution, handling and utilizing the fly ash has become a newly and closely concerned area. Currently the most promising ways of utilizing fly ash is to grind them by grinding mill, then applied them to cement mixing, mortar, fillers, bricks making and others.
Based on the current mill technology development, large-scale ultra-fine milling machine has been able to achieve a one-time ultrafine materials processing. The fine fly ash materials being processed through the mills are with uniform particle size and with improved surface activity. If added to the concretes directly they will save a lot of cement raw materials and also, they will improve the workability of concrete mixing materials and improve the plasticity and stability of reinforced concretes. Even in some cement production enterprises, people blend fly ash, in accordance with the ratio of 8%, into different cement clinkers to make cement products.
At present the main mill equipment to process fly ash include the following ones:
The first one is vertical mill machines short for vertical mill. Vertical mill uses large-scale roll system to grind high-volume materials. Compared with ordinary mill, its strength lies in large-scale equipment and operating automation. The output capacity of the usual vertical mills can be up to 100-500 tons per hour or more.The rollers of the Vertical mills are controlled by a special hydraulic system so the operation is flexible and convenient and the repair and maintenace is very easy. At present in the domestic market, vertical mill has been far ahead of many other grinding mills and Raymond mill equipment in a vary grinding processes because of its comprehensive performance of high-yield and energy-effient.
The second one is Trapezium Grinding Mill. Trapezium Grinding Mill includes Super Pressure Trapezium Mill and the newly MTW Series European Technology Trapezium Mill. The traditional grinding roller and grinding ring are designed multi-level ladder shape in the Trapezium grinding mill, which slows down the dropping speed of the materials between the grinding rollers and grinding rings and extends the grinding time to the materials; the pressure is more strong because the high pressure springs placed horizontally, which increases the fineness of the final products and the output.
It usually performances better to produce 100-800 mesh powder with a capacity of 20-50 tons per hour. The development and untilization of fly ash is wider and wider, the technical request to grinding mills technology is higher and higher. The traditional Raymond mill and ball mill on market can not meet the demand for the processing capacity and fineness in the industrial production any more. The new type of vertical mill and trapezium grinding mill will surely be the mainstream equipment in milling macchines because of their latest technological achievements and facilitate efficient performance.