vertical roller mill vrm operation

how to improve grinding efficiency of vertical roller mill

how to improve grinding efficiency of vertical roller mill

The verticalroller millis used to grind the material by using the principle of material bed pulverization. It gathers materials for grinding, conveying, powder selection, drying and separation of metal blocks and medium ore.Under normal conditions, the roller mill can run smoothly, increase production, reduce energy consumption, increase operating rate, and continuously improve economic efficiency are central issues in the management and operation of vertical roller mills.

The differential pressure of theverticalroller mill is generally controlled at5000~7000Pato ensure the proper air volume. The change of the pressure difference within the mill is mainly affected by the feed amount when other conditions are constant. Therefore, the feed amount should be stabilized.

When vertical roller mill is in normal operation, its vibration is weak. When the mill is vibrating strongly, it should be stopped and checked to ensure the equipment is working properly.There may be some reasons for the excessive vibration, and the cause should be analyzed:

Mainteining material laye thicknessr is the main content of the operation control. The stability of the material layer is a prerequisite for safe operation of the verticle roller mill. The amount of feed in the mill can be tested by 3 methods:

If raw material fineness is too coarse, it will affect the firing of the clinker. If the fineness exceeds the fine rules, the mill output will decrease and the power cent result of the raw material fineness per hour according to the laboratory. The speed of the separator is such that the fineness is controlled within therange ofR 0.0814~16%.

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vrm re-building | oasis wear tech industry [l.l.c]

vrm re-building | oasis wear tech industry [l.l.c]

Despite this from 10 years ago, some welding electrodes manufacture began to develop products and processes to rebuild parts with good results to date. Its possible to repeat 4 times the rebuilding of each set, and thanks to the enhanced wear resistance of the weld deposit, you can expect 30% additional life of each set and more than 33% saving in the spare parts and maintenance cost of the mill.

Special, self shielded, flux cored alloy wire specifically developed for the outdoor maintenance and repair welding of thick heavy components where faster weld depositing complex carboborides for wear-protective coating.

vertical roller mills

vertical roller mills

With the many advantages vertical roller mills offer, we continually develop our VRM offering with the latest upgrades, including the OKTM Mill and the ATOX Coal Mill. The OKTM Mill skilfully comminutes raw material, cement and slag. It features a patented roller and table design and concrete mill stands instead of traditional, heavy steel structures.

The OKTM Mills flexible design makes it possible to operate it with a number of rollers out of service while still reaching 60 to 70 percent of the normal operation output, minimising production losses.

The compact and long-lasting ATOX Coal Mill has the capability to grind virtually all types of raw coal, to your desired fineness. It is suitable for feed materials with varying moisture percentages, handling abrasive and sticky raw coal with ease.

The cement industrys focus on energy reduction has made vertical roller mills particularly compelling. Grinding systems in cement production make up approximately 85 to 90 percent of total plant electrical energy consumption. As vertical roller mills are 30 to 50 percent more efficient than other grinding solutions, they give cement plant owners a great opportunity to

When it comes to grinding raw coal, savings in specific energy consumption can be achieved with vertical roller mills. Specific energy consumption depends on the grindability of the raw coal and the coal meal fineness required. A dynamic separator that ensures high separation efficiency also helps to reduce specific energy use.

FLSmidth provides sustainable productivity to the global mining and cement industries. We deliver market-leading engineering, equipment and service solutions that enable our customers to improve performance, drive down costs and reduce environmental impact. Our operations span the globe and we are close to 10,200 employees, present in more than 60 countries. In 2020, FLSmidth generated revenue of DKK 16.4 billion. MissionZero is our sustainability ambition towards zero emissions in mining and cement by 2030.

vrm - the latest technology - bashundhara cement

vrm - the latest technology - bashundhara cement

Vertical Roller Mill (VRM) is the most advanced technology in cement production procedure. Bashundhara Cement has adopted VRM from LOESCHE, Germany in both the factories to ensure the best quality. With higher fineness achieved with VRM, it creates stronger and better quality concrete and thus, proves its superiority over other cement brand.

The VRM is a vertically placed large sized machine which is equipped with some rollers used for grinding raw material. It also consists of one table which is rotated by electrical motor & raw materials are feeded on the table. Due to centrifugal force on the table, raw material goes below the rollers (a gap between roller & table has to be maintain) automatically & start getting grinded. The rollers are driven by the friction between table & raw materials. The grinding process is done by exposing a bed of material to a pressure sufficiently high created by rollers which causes fracture on the individual particles in the bed. Due to such grinding, fine particles pass through the separator as the final product to the silo due to huge negative pressure in the mill & course particles falling down (separated by highly efficient separator)on the table for further grinding.

A. The grinding process of Ball mill & Vertical Roller Mill differs fundamentally. The sufficiently high enough to cause fracture of individual particles in the bed & most of the particles on the bed are considerable, smaller than the bed thickness. On the other hand, in a Ball mill, the comminution takes place by impact & attrition.

B. A suitable grinding bed is easily obtained in vertical roller mill with high efficiency separator which ensures high fineness of product. However, in the Ball mill, it is more difficult to get suitable grinding bed.

D. Particle size distribution (PSD) of the finished product obtained from VRM is much better than Ball mill product. High fineness of material ensures more dense concrete with less possibility of chemical attack.

operation guide for vertical roller mill in cement plant | agico cement

operation guide for vertical roller mill in cement plant | agico cement

The vertical roller mill (VRM) is a type of grinding machine for raw material processing and cement grinding in the cement manufacturing process. In recent years, the VRM cement mill has been equipped in more and more cement plants around the world because of its features like high energy efficiency, low pollutant generation, small floor area, etc.

The VRM cement mill has a more complex structure than other types of cement mills, so we need to ensure the following aspects are normal during the operation, or the machine may not be able to function well.

Too thick material layer will reduce the grinding efficiency of the vertical roller mill. When the pressure difference of the mill reaches the limit, the material layer will collapse and affect the operation of the main motor and the discharge system.

There are many factors that may make mill body vibrate, including the grinding pressure, material layer thickness, air volume and temperature, accumulator pressure, wear condition of the roller and the grinding plate, etc.

The grinding pressure of the mill should be adjusted according to the fed quantity, the particle size, and the grindability of the material. It must be well controlled to maintain the thickness of the material layer, reduce the vibration of the mill body, and ensure that the stable operation of the mill.

Increasing the grinding pressure will improve the grinding capacity of the mill, but the grinding capacity will stop increasing when the grinding pressure reaches a certain critical point. If the set pressure of the hydraulic cylinder is too high, it will only increase the driving force and accelerate the wear of parts, but not improve the grinding capacity.

On the other hand, too high grinding pressure will cause the thickness of the material layer to decrease, which further leads to the increase of the vibrating speed of the mill and accelerates the wear speed of the parts.

The gas temperature at the discharging port can be increased by increasing the opening of the hot air door and reducing the opening of the circulating air door. However, when the gas temperature exceeds 130 , the equipment will also be damaged. For example, the dividing wheel at the lower part of the cyclone will expand and get stuck, and the lubricating grease of the grinding roller will dry and crack, which is also unfavorable to the tail dust collection bag.

In vertical roller mills, the air volume in the mill is determined by the material feed rate. The air volume can be controlled by adjusting the power of the circulating fan of the mill or the opening of the exhaust fan at the kiln tail.

If the air volume is too large, the pressure difference in the mill and the current of the main motor will decrease, the thickness of the material layer will become thin, and the vibration degree of the mill body will become strong.

If the air volume of the system is too small, the thickness of the material layer, the pressure difference in the mill, and the current of the main motor will increase, and so will the vibration speed of the mill.

When operating the vertical roller mill, the operator must control the inlet and outlet air valves to make the air volume of the system in a balanced state, so as not to affect the air pressure at the back end of the rotary kiln.

operational parameters affecting the vertical roller mill performance - sciencedirect

operational parameters affecting the vertical roller mill performance - sciencedirect

Pilot scale VRM grinding tests were performed for gold ore grinding successfully.Effect of operational parameters on product size and product rate was investigated.Working pressure is normalized with classifier rotor speed.

Vertical roller mills (VRM) have found applications mostly in cement grinding operations where they were used in raw meal and finish grinding stages and in power plants for coal grinding. The mill combines crushing, grinding, classification and if necessary drying operations in one unit and enables to decrease number of equipment in grinding circuits. Sustainable operations and proven benefits of the technology in cement grinding applications attracted interests of the mineral industry. Within the scope of the study, ore grinding performance of the VRM was investigated via a mobile grinding plant and relationships between operational parameters were identified. In this context, gold ore was ground under different process conditions. The samples collected after the test works and size distributions were determined. As a result of the study, effects of operational parameters such as working pressure, and classifier rotor speed on product mass flow and product size were investigated. In addition, correlations of specific energy consumption of the grinding-classifying circuit with product rate and product size are presented. The aim was to develop a VRM performance prediction model that is based on input data from characterization combined with the knowledge of the interaction of the single grinding parameters.

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