Specialists journal, Steinbruch und Sandgrube, October 2010

english translation

Blending on demand

A few short steps to produce a required high quantity and quality mineral or aggregate blend.

A big contract has just arrived at the quarry, which already operates to a high quality level of clean screening and processing. However, the customer is asking for a very special unbound blend of aggregates for a road base. The contract includes the precise requirements of the new European standard, EN 13285.

If the aggregate blend doesn't exactly match this challenging specification, it could well mean problems for the customer with the controlling supervisor. The customer knows that the demands of his client cannot be met by simple wheel-loader-mixing. There is an obvious need for a sophisticated and accurate blending plant to fulfil the order.

Knowing that quarries and gravel-pits, which don't have silo conveyor-systems for blending aggregates easily and accurately, Konig Aufbereitungstechnik has developed an easy solution to this problem, which can produce in a very short space of time even unusual blends for customers with challenging requirements.

Having a considerable amount of experience arising from its rental of blending plants, the company came to market in the fall of 2009 with the completely new design incorporated in its RD 700-series. The RD 700 concept gives the quarry the ability to produce not only standard aggregate mixes, but also an almost unlimited number of special blends of material for solutions for customers with unusual requirements.

The construction of the RD 700 stands out from others by the larger than usual volume of 22.5 cubic metres or 38 tons capacity per bin and by a volume of more than 720 ton per hour in non-stop working mode. This means that the loading of a semi-trailer truck can be completed in 3 minutes.

To avoid delays due to lack of material at this speed, the breadth of each bin is 4 metres to enable the use of big wheel loaders of the 7 cubic metre class, such as the Volvo 220 or Caterpillar CAT 980 for quick and efficient feeding into the bins.

Due to the fact that the plant is on steel beams, it can be moved by one single crane lift making it extremely flexible in use. In addition, the design includes some novel features allowing the RD 700 to be transported by road without a special permit.

A steel wall allows for the easy building of the wheel-loader's ramp and a very effective emergency emptying capability is testament to the in depth working experience of the manufacturer.

As already mentioned, the high precision of mineral blends becomes more and more essential for the successful selling of quarry aggregates. To meet this requirement Konig has installed in the RD 700 a very easy-to-operate computer-based control unit, which is made of robust industrial components and includes a display showing every step in clear English while avoiding any codes or suchlike, which would necessitate access to a manual.

Owners of used equipment will be glad to hear that this control unit can also be installed to refurbish and modernise such equipment. The RD 700 design concept and control unit is also capable of integrating blending equipment where the bins are separate for bigger aggregates, screws for cement, water valves or mixers etc.

Typically for an advanced and progressive plant, production is possible in the "classic" way by stockpiling but also "on demand" by typing into the control unit the required grade and quantity and loading the blend directly onto trucks suited to the different materials on the market. Also this way of loading relieves the wheel-loader especially at busy times and offers the possibility of unmanned loading by means of a magnetic transponder system.

For more specific materials the RD 700 can be equipped by a magnetic channel or by a dosing screw conveyor for powdered or cohesive materials.

A very pleased gravel-pit owner summed up his satisfaction with his recently purchased RD 700 by saying that it will have paid itself within 18 months and the only thing he regrets is that he wishes he had bought it earlier.

As a result of the success of the RD 700, the main activities of Konig have changed from the rental business to the manufacture of blending plants for unbound aggregates and a blend of aggregates bound by cement. Because once a customer has seen the advantage of blending by plant, he will never let the machine go again.

Beside the customized and precise production of blends, the unit has also the great advantage of being able to dose the most expensive components of the blend to the highest tolerance and the least expensive to the lowest tolerance, while still remaining safely well within the specification tolerances allows for significant cost savings.

As indicated before, the RD-700 concept can also be used to refurbish older equipment either by adding the control unit or by replacing the dosing conveyors.
In early 2010, even an old blending plant, produced in the German Democratic Republic in 1980 was successfully modernised and refurbished using the RD 700 design concepts and control unit.

Specialists journal, Steinbruch und Sandgrube, Mai 2009