Loesche

LOESCHE has broken the sound barrier by selling 400 vertical roller mills for cement and granulated blast furnace slag grinding.

We can hardly keep up with demand, because LOESCHE has already sold more than 400 clinker and slag mills worldwide.

The most recent CS mills – 2x LM 53.3+3 CS – were sold to the Pakistani cement manufacturer, Kohat Cement Company Limited. The plant is expected to produce 210t/h of portland cement at a fineness of 9% R 45μm.

The success story of our plants with their patented and pioneering M+S (grinding roller plus support-roller) technology is continuing day by day.

The first LOESCHE LM 35.2+2 mill went into operation in Fos sur Mer in France in 1994. Just 10 years later (2004), a total of 50 plants of various sizes had been sold for the production of cement powder and granulated blast furnace slag. And in the next two years (until 2006), 50 more mills had been sold. In the second quarter of 2014, over 300 of our proven and reliable vertical roller mills of this type were in operation or construction.

In the last four years, a further 100 mills were sold – these numbers speak for themselves.

“With the M+S technology, we have been able to fulfil the industry’s need for a reliable and energy-efficient solution in the production of very fine cement and aggregates,” explains Dr Thomas Loesche, who is leading the third generation of the family enterprise.

“Over 400 plants sold is a great success but we will not rest on our laurels. It is our motivation to always think one step ahead into the future and to find solutions which helps our customers.”

The grinding of clinker and cement and of granulated blast furnace slag and slag in vertical air-swept grinding mills dates back to Ernst Curt Loesche’s invention. In 1927, he applied for a patent for the world’s first spring-loaded air-swept mill – the beginning of the triumph that is LOESCHE vertical roller mills. The patent was granted in 1928, which means 90 years of the modern LOESCHE mill.

However, decades were to pass until the final breakthrough of this technology for grinding clinker and granulated blast furnace slag, despite the fact that Ernst Curt Loesche had already travelled to Brazil by Zeppelin in 1935 to sign the contract and had sold the first LOESCHE cement mill LM 11 type there.

Although this new technology had technological and energy advantages over the ball mill, it was 50 years until it was able to assert itself on a larger scale.

At this time the cement industry also wanted to produce cement with the help of roller comminution which required less energy. And even though the entire cement manufacturing process was being constantly optimised, the energy-intensive clinker brick grinding process had long since been ruled out.

The reason: The requirement for the high fineness of particles lead to a dust/air mixture in the vertical roller mill, which made the grinding bed formation in the rollers difficult. For this reason, in conventional plants, each roller had to not only provide the actual communition but also the preparation of the internal grinding beds using pre de-aeration and precompaction. This caused the mill to vibrate significantly due to inadequate grinding bed formation, causing disrupted mill operation and unreliable variations in the fineness of the particles, so that the high-quality requirements of the end product could not be adhered to.

This discovery lead to the development of our patented mills for pulverization: the LOESCHE LM-CS series (cement / slag).

With the M+S technology developed by LOESCHE, these mills separate the preparation and grinding stages of the process and established an entirely new grinding-roller concept. Technically, a corresponding number of preparation or support rollers (S) are implemented in the grinding or master rollers (M), that take over the grinding bed preparation (the 2+2, 3+3 or 4+4 technology depending on the throughput). As a result, the specific properties of the very fine material can be reliably controlled. With this invention, LOESCHE has, for decades, been in the position to replace conventional grinding technology in the cement industry with vertical air-swept grinding mills. The fact that this technology is also used in the grinding of steel slag is also a success for LOESCHE.

The 2+2, 3+3 and 4+4 technology in the M+S system offers a great range of advantages in comparison with conventional grinding systems:

• Significantly higher grinding pressure
• Variable grinding pressure while the grinding plant is running and thus quickly adapt to grinding material changes.
• Very low differential speed between the grinding track and the conical, friction driven roller
• Lower specific wear during pulverization
• Compact construction due to the combination of the crushing, grinding, sorting, drying and classification process stages
• Noticeable energy saving in comparison to alternative/conventional grinding systems

Further advantages result from the grinding of blast furnace slag:

• Steep product particle size distribution
• Avoidance of ineffective product overgrinding

“Not only does the high number of sales speak for LOESCHE mills, but also especially the high number of repeat orders,” says Thomas Fahrland, Sales Manager.

“Because the economic advantages of our mills are becoming increasingly important in larger plants. Furthermore, the high operational flexbility of our units enables the grinding of all products required on the market. A quicker transformation of OPC cement into all qualities of composite cement is possible, quickly and problem-free at any time without losing efficiency.”

The fact that the development of the vertical roller mill from the LOESCHE LM-CS series has still not reached its end after such a long time is today proven by the current largest cement mill in Hub, Pakistan, with a grinding track diameter of 7.2m.

The LOESCHE mill type LM 72.4+4 CS with a drive power of 10,000kW has been sold for an OPC capacity of 445t/h and a CEM II capacity (with 10% limestone) of 485t/h at 3400 Blaine. On the grinding track, four support and four rollers cater for the projected capacity. Impressive pictures of our other plants are convincing exhibits of our company’s performance – not only in technological development but also in the construction of these plants.