Since MMD (Mining Machinery Developments) installed its first cement related Twin Shaft Mineral Sizer at the UK Cauldon Cement Works, the company has developed its Sizers to the specific needs of the global cement industry

Originally developed in 1978, The MMD Mineral Sizer was designed to meet the requirements of the demanding British underground coal mining industry. Having successfully achieved this, it became evident that the unique attributes and advantages of the MMD Twin Shaft Mineral Sizer could be applied to other underground and surface applications and industries around the world. 

The first unit in to the cement industry was delivered in the early 1980’s to Cauldon cement works in the UK (then part of Blue Circle Cement, now Lafarge Tarmac).  In contrast to the smaller 500 mm centres machines supplied to many underground coal mines, this larger primary unit with 1,000 mm shaft centres was designed to handle large pieces of shale, and proved to be an effective solution. This machine was soon followed by a 500 Series Sizer to size sticky clay containing hard material. Despite specialist clay machines being available, the issue of sizing this mixture of materials was a universal problem. Again the MMD machine proved to be an instant success, and very quickly the industry came to appreciate the unique capabilities of the MMD Twin Shaft Mineral Sizer.

In 1984 a MMD 750 Series Twin Shaft Sizer was also successfully employed to break limestone at the Cauldon Cement Works and has worked tirelessly for many years. The machine is positioned at a simple inline transfer point and recently underwent an upgrade to bring its capacity up to 1,200 tph.

Although the major portion of MMD’s interface with the cement industry is still in hard rock quarries and clay, it is by no means confined to these areas.  MMD has developed a wider product range, which now includes equipment such as its Heavy-Duty Apron Plate Feeder, as well as adapting existing products to meet the complete requirements of cement based customers.
A complete package has been supplied to customers to suit their needs. During the €265 million upgrading of Holcim’s Campulung cement plant, north of Bucharest in Romania, and following the success of previously installed MMD equipment at the Alesd plant, MMD commissioned a new clay sizing facility in 2010.

The new facility consisted of a D4 Heavy-Duty Apron Plate Feeder, a 625 Series Primary Sizer and 500 Series Secondary Sizer specifically designed to fit into an existing building.

The facility, capable of handling 300 tph and processing material from an 800 mm in-feed size to a product size of 100 mm replaced aged existing equipment which struggled with the materials sticky nature and the newly required upgrade capacity.

However, for the cement industry especially the demands of flexibility, consistency in product size and chemistry are onerous. Equipment has to handle a range of materials with very different physical characteristics, as the requirement for a chemically consistent product usually involves blending the core limestone with different often sticky materials.

A prime example is the use of the Sizer to not only break, but mix the material as well. The MMD Twin Shaft Sizer’s contra-rotating shafts and scroll action are ideal for blending the different materials, even those with very different consistencies and moisture content. An increasing number of cement plants are using the MMD Sizer in this breaking / blending role. The use of a cross belt analyser can be linked in certain applications to the variable speed drive of the Apron Plate Feeders, feeding limestone, clay and additives into the Sizer, to ensure a consistent mix of material to the stockpile and eliminating the need for separate stockpiles and the problems associated with the stockpiling of sticky clay material.
A successful complete sizing package which combines feed materials has been supplied to the Quinn Cement plant in Ireland. Here, the mixture of materials is fed through a single MMD Sizing station. The plant handles sticky clay, hard shale and limestone together and provides an efficient mixture of materials to the final blending store.

The customised package supplied consisted of a D4 Heavy-Duty Apron Plate Feeder and 625 series Primary and Secondary Sizers, handling 500 tph from an in-feed of 1,000 mm and giving a product size of 100 mm.

MMD has also installed a host of semi-mobile units, as well as a significant number of low (under 1,000 tph), medium (2-3,000 tph), and high capacity (over 5,000 tph) fully mobile Sizers around the world.  The company’s know-how and experience enables it to offer the best possible solutions, including those with the inherent benefits of mobility to the cement industry.

As well as the many new plants where the MMD Sizer package was designed to fit into the plant from the outset, there have been numerous examples of cases where the installation of an MMD Sizer has either replaced or supplemented the existing equipment when problems have been encountered. For example, in Belgium an MMD 625 Series Sizer was installed in a plant that had been running for many years, where the ever increasing stickiness was causing problems for the existing roll crusher.  The compact size and low profile allowed MMD to install the Sizer on rails over an existing conveyor line, thus involving minimal expense and complication.

Similarly, another cement plant, designed and installed by one the worlds leading cement manufacturers suffered severe production hold-ups due to the amount of clay in the system.  The problem was put to MMD, who quickly resolved the situation with a simple installation of a 500 Series Sizer at a cross belt transfer point that fitted within the existing plant, successfully allowing the plant to run at full production.

Some of the most recent orders won by MMD to supply equipment to the cement industry include:
• A 500 Series Twin Shaft Sizer to process 300 tph of clay, from an in-feed size of 350 mm to a product size of 50 mm, for an Ital Cementi plant in Italy.
• A 500 Series Twin Shaft Sizer to process 130 tph of Jurassic and Quaternary clays, from an in-feed size of 600 mm to a product size of 150 mm following poor results from existing equipment for Basel Cement in Russia.

MMD’s existing record within the cement industry and the established features and benefits of the Mineral Sizer has led their technology to a variety of cement producers worldwide, working closely with Holcim, Cemex, Lafarge, Heidelberg, Italcementi, CRH, Buzzi, Titan Cement and Eurocement as well as with leading cement plant designers such as FLSmidth, Polysius, ZEMDES and KHD. Today through innovative product design, MMD size over 70 different minerals worldwide, providing technological solutions to mineral reduction in many varied process industries and can justifiably lay claim to a position amongst the leading mineral processing suppliers to the cement industry.