Grinding equipment and application (3)

In order to avoid polluting the air and reducing the wear of the pipeline and the main fan impeller, cleaning measures must be taken to ensure that the return air dust concentration in the return air line is very low. According to the actual measurement, the iron ore dust concentration in the return air stream in no more than 5 to 6 g / m 3, the main fan wheel does not wear out quickly; for smaller fan return air stream to allow a high dust concentration may be 8 ~ 9 g / m ³ . Because air purification consumes a lot of energy, large-scale self-grinding machines use closed-loop systems. The closed-air air system is characterized by a main air path and an auxiliary air path; the former is mainly used for material transportation and grading, and the latter is used for purification. The main functions of the auxiliary wind road are two: (1) to ensure that the main air path has sufficient negative pressure; and (2) to exhaust air to reduce the dust concentration and moisture in the return air flow of the main air path. According to theoretical calculations and practice, the amount of exhaust air from the auxiliary fan is about 1/4 to 1/6 of the air supply volume of the main fan. The disadvantage of closed-loop systems is the complexity of the process.
B Wet Self-grinding Machine The structure of the wet self-grinding machine is shown in Figure 13. It is also characterized by a large diameter and a short length, but its long diameter is larger than that of a dry self-grinding machine, generally 0.3~0.5. In recent years, in order to increase the output of the mill, a wet self-grinding machine with a large cylinder length has been created. The structural characteristics of the wet self-grinding mill are: the two end caps of the ore and discharge are cones themselves, the cone angle is about 150°, and the middle part of the cylinder is slightly concave. The purpose of this configuration is to make the material in the mill be squared into the cylinder and mix it to prevent "particle size segregation". The wet self-grinding machine is more prone to “segregation” than the dry self-grinding machine. The reason is that the long-diameter is relatively large, and the force of carrying larger particles when the slurry flows to the discharge end in the wet self-grinding machine is more dry than the dry self-grinding machine. The airflow in the mill has a greater carrying capacity. Therefore, in order to prevent the discharge of large materials, a grid plate is installed at the discharge end of the wet self-grinding mill. This kind of grid plate can also accelerate the discharge and reduce the over-grinding of the material.
The drainage grid plate of the wet self-grinding machine is different from the lattice type ball mill . The latter has a grid on the grid on the center line of the cylinder to the center line of the cylinder, and the drainage grid of the wet self-grinding machine has a height on the baffle near the center of the cylinder toward the center of the cylinder. There is no cell hole. According to this height, the wet self-grinding machine is divided into low-level ore discharge, medium-level ore discharge, and high-level discharge. The discharge level can be adjusted according to the production requirements by replacing the non-size hole baffle.
The discharge end of the wet self-grinding mill is generally equipped with a self-return device (Fig. 14). The self-returning device is similar to a cylindrical sieve with a counter-spiral that rotates with the mill. The material larger than the mesh hole is returned to the self-grinding machine by the reverse spiral action, and the material smaller than the mesh hole is leaked and enters the lower stage process.
Figure 15 shows the type of liner of the wet self-grinding mill. The height of the lifting plate and the spacing between the two lifting plates greatly affect the movement state of the material in the self-grinding machine, that is, the production index that affects the grinding machine. [next]

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Since a wet mill liner materials, in addition to using steel alloys (e.g., high manganese steel, and the hard nickel-chromium-molybdenum steel actinides) than material, but also successfully used in recent years rubber lining of non-metallic material, which is a The "high"-"low" type staggered rubber bead lining is also a special rubber lining for the wet self-grinding barrel. It is generally believed that the height of the "high" rubber bead lining protruding from the cylindrical rubber lining is approximately equal to the maximum ore mass, and the "low" lining is just right when the "high" lining is half worn. All worn away. In this way, the mill always uses a new “high” liner to replace the “low” liner during the entire production process, thus maintaining the “high” and “low” shape of the rubber liner during the grinding work. The correct relationship ensures the stability of the self-grinding machine.
The wet self-grinding machine is driven in the same way as a dry self-grinding machine. Small-size self-grinding machine, for example, D≤6.0 m, generally driven by a single motor; large-size self-grinding machine is driven by a dual motor. The φ7.5×2.5 m wet self-grinding machine manufactured in China is driven by two motors, each of which has a power of 1000 kW.
(6) Gravel mill and block mill The gravel mill is used as the grinding medium. The gravel mill is mainly used in the following three occasions: (1) The material to be ground is strictly prohibited from mixing with iron metal, so as not to affect the quality of the product or the next processing steps, such as chemical and ceramic industries; (2) some useful minerals are very Soft, using metal grinding balls as grinding media is easy to cause over-grinding, such as regrind operation of molybdenum concentrate or medium ore, (3) in order to improve the output of wet self-grinding machine, remove enough hard-to-grind particles from the self-grinding mill as gravel Grinding media. [next]
The structure of the gravel mill is the same as that of the ball mill; both can be used universally. Since the density of the gravel medium is much lower than that of the metal medium, the processing capacity of the gravel mill is also much lower than that of the ball mill. In order to prevent gravel discharge, the gravel mill uses a grid type discharge.
The gravel mill liner can be made of non-metallic materials such as ceramic tiles and silica bricks, but rubber liners are particularly suitable. When the size of the gravel medium is less than 90 mm, the use of a rubber liner in the gravel mill is more economical than a steel liner. The cylinder rubber lining consists of a layered lining and a flat lining. The production practice shows that the shape of the rubber lining and the rotation speed of the mill have a great influence on the increase of production and energy saving of the mill. When the critical speed of the mill is 63%, the grinding capacity of the “K” rubber bead lining (Fig. 6h) is 30% higher than that of the square rubber bead lining, and the unit power consumption is reduced by 20%; when the critical speed is 75 In %, the former is only 10% more than the latter, and the power consumption is only reduced by 10%. The use of the rubber grid plate to replace the cast steel grid plate of the gravel mill for discharging, can effectively prevent the blockage of the pupil and reduce the wear of the grid plate.
Since the 1980s, Nordic developed and promoted a grinding process called "Auto-komp" type which can be used in general rod mills or ball mills (eg ф4.0×6.0 m, ф 3.2×4.5 m). As a block mill, a large ore larger than 100 mm is used instead of a metal rod or a ball as a grinding medium to process a material of less than 30 mm; less than 100 is larger than a size of 30 mm, that is, a generally difficult-to-grind particle is used as a gravel grinding medium. In order to facilitate the discharge, the discharge opening of the block mill is relatively large, and in order to increase the production capacity, the long diameter is generally much larger than that of the conventional mill.

A4 Paper Machine

A4 Paper Machine

This is A4 Paper Making Machine,writing and printing paper making machine.

According to the different paper grade and working speed, this kind of paper machine is needed to select the way of papermaking, dewatering structure of press section, dryer cylinder bank, sizing and finishing equipments.

Sheet forming can use the open-type headbox, air-cushion headbox, and hydraulic headbox, gap former and inclined wire former. According to the paper uniformity requirement, it can use distributor roll or finishing surface roll.

Press dewatering type is multi-roll and multi-press nip press rather than large-diameter press. As the low basis weight and wet strength of this kind of paper, it usually makes the low strength wet sheet attached to the felt or guide rolls during each section mutual transferring and full web leading as much as possible.

Dryer section: dryer cylinder group. Paper leading: active or passive paper rope system. Finishing equipment: To choose according to the paper grade requirement.

Now we introduce the technical proposal and structural drawing of Fourdrinier advanced printing paper machine, which we made for Taiqian Minrui Huatong Paper Company in Henan province, China. The advanced printing paper of this company is the famous brand in China.

Trimmed width: 2640mm

Working speed: 400m/min

Basis weight: 50-100g/sq.m.

Headbox: Air-cushion headbox

Forming table length: 15m

Suction flat box with all stainless steel micro-crystal cover.

Press section: four rolls two press nips

The wet sheet is stripped by pick-up suction unit.

The second under press nip rubber blind bottom roll diameter is Φ800mm, with drive unit;

The suction top roll diameter is Φ800mm, with drive unit.

The top press nip is made by a stone roll and a rubber roll. The rubber roll diameter isΦ800mm, with drive unit;

The stone roll diameter is Φ850mm, with cut squirt.

This structure ensures the low strength wet sheet can press smoothly and paper breaks can be reduced.

The smooth press rubber bottom roll diameter is Φ800mm; the top stone roll diameter isΦ850mm. The paper leading roll has the drive unit.

The dryer section has 32 dryer cylinders with the diameter of Φ1800mm, which is divided into five groups: three groups for before-sizing, two groups for after-sizing. The top and bottom felt of first group and the group at the back of sizing machine is equipped with six felt drying cylinder with the diameter of Φ1250mm, which can dry the moisture well and improve the drying efficiency.

The paper leading roll has the drive unit. The paper leading type is three-stage passive paper rope system.

Sizing machine: inclined type surface-sizing machine.

Calender: four roll three press nips; the number is decided by the demands.

Reeler: horizontal pneumatic reeling machine.

If you are interested in our products, please feel free to contact us for more information, we are glad to give you the competitive quotation upon receipt of your detailed requirements.

A4 Paper Making Machine,A4 Paper Machine,Writing And Printing Paper Machine,A4 Copy Paper Making Machine

Dandong Tianshin Automatization Technology Co.,Ltd , https://www.ctpmmachine.com