Sometimes it’s as easy as one plus one, especially when it concerns transferring a well proven solution for another application. This is exactly what the engineers at allmineral have done, thereby opening up a new dimension in gravel processing.

The first ‘1’ in the equation: a proven vibrating discharge feeder from allmineral’s iron ore jigging machines which allows the accurate discharge control of large particle beneficiated material. The second ‘1’: the jig tailor-made for coarse gravel is now enjoying growing demand thanks to the increase in economic activity in the construction industry.

The result: alljig7#174;-GR, the new coarse-grain gravel jig, which has been presented to a large audience in Munich at the Bauma. The alljig-GR, featuring a customized vibrating feeder discharge, is breaking all the barriers and setting new standards. So far, the limit for the feed material was approx. 60 millimetres.

This has now been increased to process materials with particle size up to 100 millimetres. “The alljig-GR is therefore of special interest to our customers in the Alps, with far coarser geological deposits,” says Thomas Neumann, responsible for this business area at allmineral. “This type of material can now be cleaned in a single step. To date, coarse material greater than 60 millimetres had to be crushed before running them through the jig for upgrading.”

“We noticed the market for gravel and sand developing in Germany,” says Neumann. “Building material construction is clearly in the midst of a recovery period.” For allmineral, the number of orders received has been on the rise since mid-2006. In the meantime, Duisburg sold its 200th gravel jig including the five units ordered in the previous year for the German market. Another high satisfactory fact is that producers of building materials are using the complete allmineral range of products in the processing sector. These include two plants where they have added an allflux, so that they can remove all of their light-density material from sand fractions.

While developing the alljig-GR, allmineral’s engineers solved the question of how to adapt the ore technology. Cross-sections had to be enlarged and the design had to be changed to accommodate the new height of the material layers and the resultant water demand. “The greatest challenge though,” Neumann explains “was the discharge control, since the level of the clean gravel layer has to be stable during the entire jigging process.”

To ensure permanent stability, the software for the automatic discharge control had to be reprogrammed to allow the floats to detect larger level variations when the gravel is coarser. Compensating for these larger variations when coarser particles are discharged requires a more sophisticated control to ensure no loss in quality. So now, with its alljig-type GR, allmineral can assure its customers a 99,99% grade for the material, even with gravel particle sizes up to 100mm.