Vertical roller mill raw material recycling technology

5000t / d production line of raw material preparation using RMR57/28/555 vertical roller mill. In the trial production period, there are often caused by improper operation of bucket elevator loop current is too high, resulting in crushing bucket elevator, mill jump stop the phenomenon, not only to field a larger increase in the workload of staff, also affected production. Through the operator and the constant review and practice, the current form of a set of effective control measures to effectively prevent the occurrence of such phenomena.

Problems outside the circle bucket elevator model: NSE300 × 33350, transmission capacity of 450t / h, motor power 75kW, rated current of 140A, the alarm value of 150A. In actual production, often due to sudden changes in raw materials, incoming instability and other reasons, the status changed to wear, resulting in material outside the circle, resulting in high current hoist. Early in the production, operation of commonly used method is a rapid reduction of the volume of feed at the same time increase the grinding pressure, appropriate to reduce the speed of the powder, so that as many as possible with the gas from the powder mill, mill to reduce the volume within the material, thereby reducing the external of recyclable materials. However, in practice found that such methods of operation to adjust for too long, large number of materials from outside the mill, will eventually cycle crushing bucket elevator. As the hoist is a chain of relations with the vertical roller mill, skip hoist will stop after the mill shut down.

Improvements through exploration and discovery, when the cycle of bucket elevator reach the threshold current 140A, even to the alarm value of 150A, to take the following measures, which can effectively avoid the cycle of bucket elevator of death.

① trip into the grinding belt, prohibited materials into the vertical roller mill. ② to quickly lower the ground pressure, so that in the disc of material formed on a temporary thick layers, so that the cycle bucket elevator plummeted materials. ③ appropriate separator to reduce speed, so that in fine grinding as soon as possible from outside the mill (separator speed should not be too low to prevent the raw material through the rough.) ④ When the cycle of current bucket elevator downward trend and dropped to 140A, can reduce the feeding amount to 200 ~ 300t / h, open the feed into the grinding belt, adjust the grind to a steady state condition, then normal operation.

Practice has proved that such methods of operation is simple, rapid decrease in a relatively short period of time outside the volume of recyclable materials to effectively prevent the large amount of recyclable materials caused by circulating outside the bucket elevator crushing, grinding stop jumping phenomenon long-term operation of the mill has played a crucial role, thus ensuring the normal kiln feed, but also greatly reduces the power consumption of raw material grinding system