300,000 tons annual production line case of slag vertical mill

  • Processing material: coal gangue
  • Feed particle size: <20mm
  • Finished particle size: 200 mesh, D90
  • Water content of finished product: <1%
  • Capacity: 75 tons/hour
  • Equipment composition: one VRM2800S vertical mill (1400kw), feeder, elevator, raw material bin, screw feeder, vertical mill, dust collector, fan and control cabinet, etc.

Project Overview

A company has a 5000t/d precalcined rotary kiln clinker production line, which is equipped with two MVS4600 raw material roller mills in parallel. Due to the high failure rate of equipment, frequent start-up and shutdown, large maintenance workload, low output during raw meal roller grinding, high power consumption in the raw meal process, and at the same time, the 0.2mm sieve of the raw meal is coarse, and the raw meal KH is qualified The rate is low (30%-40%), which seriously affects the stable calcination of the rotary kiln, resulting in poor clinker quality and high comprehensive clinker power consumption. After continuous exploration and adjustment by professional technicians and a series of technical measures, the output of raw meal roller mill has been continuously increased, the comprehensive power consumption of raw meal process and clinker has been reduced, the fineness of raw meal after grinding is finer, and the pass rate of raw meal KH improve.

Challenge Or Need

Introduction to shaft kiln

Frequent cutting of clay material leads to frequent stoppage of raw material grinding, and the KH qualified rate of raw material is low, which affects the stability of the thermal system of the rotary kiln system.

The speed of the raw meal roller mill powder separator is about 1350r/min, which is 93% of the rated speed, but the fineness of the raw meal is still relatively coarse (the sieve residue of 0.2mm is between 3% and 5%), which seriously affects the cooked food. The calcined quality of the clinker leads to higher clinker fCaO.

The output of the raw meal roller mill is relatively low, about 190t/h, and the power consumption of the raw meal process is as high as 22-23kWh/t.

Analysis of main reasons

The clay feeding system is composed of clay round warehouse + small warehouse + electronic belt weighing scale. Due to the high moisture content and strong viscosity of the clay, the clay warehouse and small warehouse are often filled and blocked, and the clay material is frequently broken, resulting in raw material KH The pass rate is only 30% to 40%. At the beginning, 4 air cannons were installed around the small warehouse, and the air cannons were used to clean up the material blocking, but the phenomenon of material breaking has not been improved, and the manual material is frequently broken, and the labor intensity is relatively high. After analysis, it is believed that the small size of the discharge opening of the small clay silo is the main reason for the clogging and breaking of the clay material.

When the 0.08mm sieve residue of raw meal is controlled at 14% to 16%, the 0.2mm sieve residue is about 3% to 5%, resulting in high clinker fCaO, low pass rate and low clinker strength.

A comprehensive inspection of the raw material roller mill found that the gap between the seal rings of the powder classifier is relatively large, and the axial gap is 30-40mm, resulting in roughness of the raw material fineness. is 120mm, the minimum clearance is 10mm, and some blades are loose and shifted.

The hot air duct at the entrance of the raw meal roller mill has a corner of about 70°, with a lot of accumulated material and relatively large resistance. The negative pressure at the entrance of the raw meal roller mill is about -2000Pa.

Implementation process

describe the implementation process of the mechanical equipment, including equipment installation, commissioning and integration with existing systems or processes.


1、Change the width of the belt scale from 1.2m to 1.6m, and expand the width of the discharge opening of the small clay bin from 1.0m to 1.4m. At the same time, install a cut-off sensor signal switch on the belt scale, and add two electric vibrators to the small bin. When the belt scale breaks the material, the induction switch gives a start signal to the electric vibrator, and the electric vibrator starts to clean the material, which greatly reduces the phenomenon of material breaking. The pass rate of raw material KH after grinding has been greatly improved, from 30% to 40% to about 70%.

2、Treat the sealing ring of the powder classifier. Extend the inside of the upper sealing ring to lengthen. Lengthen 30mm for the first time, reduce the speed of powder classifier to 1200r/min, and reduce the sieve residue of 0.2mm of raw meal to 2%~3%; The 0.2mm sieve residue is reduced to 1% to 2%.

3、Adjust static blade clearance and connection fixation. According to the wind speed control between the static blades of the powder classifier is about 18m/s, it is determined that the static blade gap should be 40mm, and the static blade gap of the powder classifier is uniformly adjusted, and all static blades are welded and reinforced with steel bars to prevent displacement. See Table 1 for the comparison of raw meal fineness changes before and after the adjustment of the powder classifier. By increasing the loading pressure of the raw meal roller mill, reducing the particle size of the limestone entering the mill, reducing the height of the retaining ring, and increasing the output of the raw meal roller mill. The loading pressure is increased from 8.0MPa to 9.0MPa; the particle size of the limestone entering the grinding is firstly reduced from 80mm to 70mm, and then from 70m to 60mm; To 70mm, the corresponding current drops from 130A to 110A, from 110A to 100A, and from 100A to 90A. The output of raw material roller mill has been greatly improved. The adjustment process and effect are shown in Table 2.

4、Results and benefits: Emphasize the actual effects and achievements of the machinery and equipment, such as data and actual performance in terms of production efficiency improvement, cost reduction, and quality improvement.

Table 1 Comparison of raw meal fineness before and after adjustment of powder classifier (%)

Table 2 Adjustment process and effect of raw material roller mill

Renovate the raw material roller mill hot air pipeline, add two pipelines in parallel on the basis of the original hot air pipeline, the grinding resistance is significantly reduced, the negative pressure is reduced to -1000Pa, and the grinding temperature rises by 10°C. Figure 1 is a schematic diagram of the transformation. Table 3 shows the change of negative pressure at the entrance of the roller mill before and after the transformation of the hot air pipeline.

By adopting the above technical measures, the output of the company's two raw meal roller mills increased by about 25%, the power consumption decreased by about 3kWh/t, and the 0.2mm sieve of raw meal was reduced from 3% to 5% to 1% to 2%. , The pass rate of raw meal KH is increased by about 35%, and considerable economic benefits have been achieved.

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