Raw mill is made up of feeder part ,discharging part ,rotating part ,transmission part(reducer,samll transmission gear ,motor,electric control) etc. It's a key equipment for grinding materials, widely used in powder-making production line such as cement, silicate sand, new-type building material, ore dressing of ferrous metal and non-ferrous metal, etc. Do your know how does the raw mill work in the cement plant? This paper mainly introduces the raw mill in cement plant.
In order to achieve the desired setting qualities in the finished product, a quantity (2-8%, but typically 5%) of calcium sulfate (usually gypsum or anhydrite) is added to the clinker and the mixture is finely ground to form the finished cement powder. This is achieved in a cement raw mill. The grinding process is controlled to obtain a powder with a broad particle size range, in which typically 15% by mass consists of particles below 5 m diameter, and 5% of particles above 45 m. The measure of fineness usually used is the "specific surface area", which is the total particle surface area of a unit mass of cement. The rate of initial reaction (up to 24 hours) of the cement on addition of water is directly proportional to the specific surface area.
The cement is conveyed by belt or powder pump to a silo for storage. Cement plants normally have sufficient silo space for 120 weeks production, depending upon local demand cycles. The cement is delivered to end-users either in bags or as bulk powder blown from a pressure vehicle into the customer's silo. In industrial countries, 80% or more of cement is delivered in bulk.
Our raw mill has been widely used in the cement making plant. In a large number of customer feedback, we received a lot of enthusiasm and positive reaction. They speak very highly of our machines. According to a lot of customers' response, this plant generally have the following four advantages.
Raw mill is generally called cement raw mill, raw mill in cement plant, it refers to a common type of cement equipment in the cement plant. In the cement manufacturing process, raw mill in cement plant grind cement raw materials into the raw mix, and the raw mix is sent to the cement kiln to make cement clinker, next, clinker and other admixtures will be ground into finished cement by cement mill.
As for the type of raw mill, there are two types including cement ball mill and vertical cement mill. In the traditional cement raw mill system, the cement ball mill system is more typical. After technology modification, the vertical cement mill has obvious advantages compared with the cement ball mill, and it is suitable for the large cement production line.
AGICO CEMENT is a raw mill manufacturer from china who has the ability to manufacture cement ball mill and vertical cement mill. As a leading and trusted manufacturer, we had exported many projects of cement raw mill and cement equipment to the countries or regions around the world. Why AGICO CEMENT is popular?
Vertica raw mill, also known as vertical roller mill, in the 1920s, the first vertical raw mill in cement plant is designed in German. It is widely used in cement, electric power, metallurgy, chemical industry, and other industries.
Low investment: the vertical raw mill set crushing, drying, grinding, grading transportation in one, simple system, compact layout, less space, it also can be arranged in the open air, save a lot of investment costs.Low operation cost: small energy consumption and less damage reduce the running cost.Environment protection and clean: small vibration, low noise, and good sealing, the system works under negative pressure, no dust overflow.Stable quality of raw mix: because the material stays in the raw mill for a short time, it is easy to detect and control the product size and chemical composition, reduce repeated grinding, and stabilize the product quality.
The main motor drives a millstone by rotational speed reducer, at the same time the wind enters into the raw mill from the air inlet, material through the screw feeder fell in the middle of the raw mill, under the action of centrifugal force, the raw materials move uniformly from central to the edge of the millstone, the materials will be ground by the roller when it passes through the grinding roller way, large materials are directly crushed. Crushed material continues to move to mill edge, until being taken away by the wind ring in strong turbulence, and larger particles material again fell to the mill to continue to crush, the flow of materials through the upper part of the separator, in the effect of separator blade, coarse particle back to the grinding mill, qualified fine powder with airflow is out of the raw mill, and collected by the powder collection.
The cement ball mill usually can be applied to raw meal grinding or cement grinding. Besides, the cement ball mill also can be used for metallurgical, chemical, electric power, other mining powder grinding, and other grindable materials.
Safe and reliable system: the maintenance of the reduction gear and gear is more convenient, firm and wear-resistant, and also reduces the downtime, maintenance time and the labor intensity of the operators.
Good wear resistance and long service life: Cement ball mill adopts the high-quality wear-resisting material, and the lining can be removed, therefore the service life of the equipment or vulnerable part is all longer.
The main working part of cement ball mill occurred in the low-speed rotary cylinder, when the cylinder is drove to rotary, grinding medium is attached on the liner to rotary together due to the effect of inertial centrifugal force, and taken to a certain height, freely fall because of gravity, grinding medium break the materials in the cylinder body, at the same time the grinding body in the rotary raw mill have circular motion, also can produce sliding and rolling, which result in grinding among the grinding medium, liner, and materials. When the material is crushed and ground by impact, the material flows slowly from the feeding end to the discharging end to finish the grinding operation.
The raw mill is a kind of necessary cement equipment in the cement plant. In the real working condition, but the large configuration will produce a bad effect on the cement plant, so it is very important to set a reasonable configuration of the raw mill. There are five reasons why we control the configuration of the raw mill in cement plant:
Composition fluctuation of the raw meal: The frequently start-stop of a raw mill will bring different degrees of influence on the quality, whether it is the cement ball mill, the vertical cement mill or the cement roller press system.
Raw mill is mainly used in grinding raw materials and end products in cement plant. It is also suitable for various ores and other materials metallurgy, mine, chemical and construction. Besides, it has two forms of milling, one is an open form, and the other is a recycle close form equipped with powder concentrator.
The raw mill uses pressure and shear generated between the rollers and the rotating table to crush and grind raw materials. Feed material is directed onto the grinding table by the feed chute. The rotation of the grinding table accelerates the material towards the grinding track and passes it under the rollers. Partially ground material passes over the dam ring encircling the grinding table and into the hot gas stream coming from the nozzle ring.
Raw meal grinding is a vital link in the cement raw material preparation process. After the cement raw material is crushed, it will be sent into the raw mill for further grinding until a certain degree of fineness is reached, and then enter the clinker calcination process. From the production experience of many cement plants, the selection of cement equipment, especially raw mill, will directly affect the project investment, production schedule and economic benefits. At present, in order to adapt to the process characteristics of the new dry method cement production line and make full use of the exhaust gas residual heat of the kiln tail preheating decomposition system, we usually adopt the grinding system that merges drying and pulverizing into a single.
AGICO is an experienced Chinese cement equipment manufacturer. We have been in the cement industry for almost 20 years, specializing in cement EPC project exporting and cement making machines exporting, such as cement production line, cement kiln, cement crusher, cement mill cement raw mill, etc. According to the different properties of materials, there are mainly two kinds of grinding systems used in our cement plant.
The cement ball mill manufactured by AGICO can complete the drying and grinding of raw materials at the same time. After entering the ball mill, materials directly contact with the gas with high temperature, so the heat exchange and the water evaporation is fast. Under normal conditions, we usually divide the cement ball mill grinding system into an intermediate discharge circulating grinding system and tail discharge circulating grinding system.
Intermediate discharge circulating grinding system is a drying form in the cement ball mill. In terms of drying function, this system is the product of the combination of wind swept mill and tail discharge circulating grinding mill. In terms of grinding function, it is equivalent to a secondary closed-circuit grinding system. After classified by the powder concentrator, most of the raw meal will go back to the fine grinding chamber and a small part to the coarse grinding chamber. This is better for the hardness and granularity adaptability of raw materials.
The main difference between the tail discharge circulating grinding system and the air swept mill is that materials in the tail discharge grinding system will first pass through a drying chamber before reaching the grinding chamber. Besides, this system adopts the mechanically discharging method. The hot air will be transferred from the head to the tail, and then discharged into the atmosphere after dedusting by the dust collector.
Cement vertical mill, also called roller mill, is another raw mill commonly used in cement plants. Compared with the cement ball mill, it has a great difference in structure, grinding principle, process layout, automatic control, and energy consumption, which play an important role in the modern cement industry.
AGICO Group is an integrative enterprise group. It is a Chinese company that specialized in manufacturing and exporting cement plants and cement equipment, providing the turnkey project from project design, equipment installation and equipment commissioning to equipment maintenance.
The production of cement is one of the most power-intensive and harmful gas-emitting processes in the world. The energy policies of many developed and underdeveloped countries focus on increasing energy efficiency in the industry, which in turn causes decreased harmful gas emissions. In this chapter, energetic and exergetic analyses of a raw mill in a cement facility were performed for a better understanding of the system design dynamics. The exergy destruction rate and exergy efficiency were obtained by using the mass and energy and exergy balance equations. The exergy destruction rate and exergetic performance of the raw mill system in the cement plant were calculated to be 2940kW and 34.67%, respectively. In addition, the system design parameters that affected the process performance, such as the ambient temperature, mass flow rate, and component temperature, were analyzed.