Our company’s（Beijing Liulihe Cement Co., Ltd.）integrated cement grinding system has a production capacity of 1 million metric tons, with PO42.5 cement as its main product. There are two production lines, each equipped with a Ф4.2 × 13-meter tube mill as the main unit, with a production capacity of 160–200 t/h. Related auxiliary equipment includes: an HFCG160-140 roller press, an HFV400V classifier, an NSE100 × 43.825-meter bucket elevator, and an HHL-250(D) mechanical mixer. The original mechanical mixer had a maximum production capacity of 300 t/h, a mixing uniformity deviation of ±2%, and a main shaft speed of 80–120 r/min. The reducer model is H2SH7-12.5-A, with a speed ratio of i=12.5; it is imported equipment. The motor model is Y2-315S-4, with a power rating of N=110 kW. It is installed and operated to add ultrafine powder before the finished product enters the bucket elevator.
The original mechanical mixers were put into service at our company（Beijing Liulihe Cement Co., Ltd.）in early 2012. The investment for each unit was 400,000 yuan, totaling 800,000 yuan for the two units. Shortly after the equipment began operating, dust leakage was detected. Six months later, the leakage had become extremely severe, causing significant environmental pollution at the site. A dedicated worker had to be assigned to clean up the area during every shift. Due to the large volume of leaked dust, a loader was required to assist with its removal, and the leakage also shortened the service life of the bearings. Bearing failure, in turn, placed a heavy operational load on the entire unit, causing the motor to frequently trip and shut down.
Frequent breakdowns severely hampered production continuity. Although we later implemented measures and established a strict monthly inspection system, we were unable to reduce equipment failures. Each breakdown took more than eight hours to resolve, and on-site workers faced high labor intensity and poor working conditions. The equipment had become a bottleneck in the grinding production line, causing significant headaches for the production, technical, operational, and electromechanical maintenance departments. Additionally, due to the equipment’s bulky mechanical structure, high wear and tear on parts, and significant power consumption, our company began searching for a replacement.
Our technical staff came across an article in *Cement* magazine featuring a pneumatic-mechanical composite mixer manufactured by Shanxi Longzhou Conveying Machinery Co., Ltd. Its low overall power consumption, high operational efficiency, excellent mixing performance, and flexible installation options caught our attention. We immediately called the company to inquire about the product, and they promptly dispatched a highly experienced sales engineer to our site to assist with design and model selection. We subsequently signed a contract for one FH800*4000-2 pneumatic-mechanical composite mixer, the compound mixer will soon be put into operation.
This composite mixer is a twin-shaft mixing type. Each shaft is driven by a domestically manufactured XWD5 cycloidal pinwheel reducer, with a drive motor rated at 5.5 kW. A domestically manufactured RSR125-7.5 kW Roots blower at the bottom of the mixer supplies air. The mixer’s total power consumption is 18.5 kW. It features a top-feed, bottom-discharge design and has a mixing capacity of 500 m³/h, it is ready for use immediately after installation.
After being put into operation, all technical indicators met expectations; the equipment operated smoothly with an uptime rate of over 95 percent; there were no material leaks; on-site hygiene conditions were effectively improved; transportation costs associated with manual and mechanical dust removal were eliminated; mixing uniformity was ensured; and cement quality was enhanced. Deviations in all measured indicators at the mixer outlet were within ±2 percent.
Feedback from various departments regarding the replacement of the first Pneumatic-Mechanical Composite Mixer：
Operators: It has reduced the physical strain of the work and meets standardisation requirements.
Technical Department: The mixer features advanced mixing technology and delivers significant energy savings.
Production Department: Operational reliability is assured; it starts whenever required.
Electromechanical Maintenance: It has a low failure rate, is easy to operate and has required no maintenance this year.
Following the commissioning of the first composite mixer, both the mechanical mixer and the composite mixer were operating simultaneously. This situation fully highlighted the various shortcomings of the original mechanical mixer and the numerous advantages of the composite mixer. Three months later, in response to strong requests from the Grinding Workshop, the Production and Technology Department submitted a report to the company’s management requesting the replacement of another mechanical mixer. The company’s management promptly approved the request and urged the Procurement Department to swiftly procure a second composite mixer from Shanxi Longzhou Conveying Machinery Co., Ltd.
Following the commissioning of the second composite mixer, the grinding workshop completely transformed its previously reactive production situation, making production scheduling a reality. There is no longer any need for staff to constantly monitor and clear overflow material on site, the mechanical and electrical maintenance staff no longer have to worry about this issue, and energy-saving benefits continue to increase.
Our company has made a rough estimate of the electricity savings achieved by the two composite mixers. The original mechanical mixers had a power rating of 110 kW each, whilst each composite mixer has a total installed power of 18.5 kW. The hourly electricity saving is 110 – 18.5 = 91.5 kW. Calculated on the basis of 10 months (7,200 hours) per year at a rate of 0.58 CNY per kWh, 91.5 × 7,200 × 0.58 = 382,104 CNY (57,083 USD). The two composite mixers can save 764,208 CNY (114,166.54 USD) annually.
If converted to standard coal, based on 3.27 tonnes of standard coal = 10,000 kW·h, the two mixers save 91 × 7,200 × 2 = 1,317,600 kW·h per year compared to the original mechanical mixers, which equates to 430.86 tonnes of standard coal (1,317,600 kW·h ÷ 10,000 × 3.27), whilst simultaneously reducing CO₂ emissions by 430.86 × 2.62 = 1,128.85 tonnes and SO₂ emissions by 430.86 × 0.0085 = 3.66 tonnes. Emissions of NO and NO₂ were reduced by 430.86 × 0.0074 = 3.19 tonnes.
The economic and social benefits to the enterprise are immense. The investment in a single composite mixer can be recouped in less than four months through the savings on electricity bills alone, making it truly excellent value for money.
Having used the composite mixer for nearly a year, we believe it to be a technologically advanced and innovative piece of equipment in the field of cement grinding. It combines the advantages of pneumatic and mechanical mixing, featuring an advanced mixing mechanism, significant energy savings, uniform and reliable mixing, high operational availability and maintenance-free operation; it is a mixing device of international advanced standard.
We venture to suggest that, if this equipment to be adopted across the majority of new dry-process lines and cement grinding plants, it would not only generate substantial cost savings for these enterprises but also make a significant contribution to reducing global carbon emissions.
Hello, I am the online customer service
