Modernization of a quarry’s high-grade chippings operation
Jost’s diabase quarry in Altenkirchen, Germany, wanted to increase the percentage of high-grade chippings that the quarry produced. The aim was to expand the capacity to produce the more popular and higher demand fractions, while remaining flexible in order to meet future requirements. Although significant modifications needed to be made to the existing plant, the planning and installation phase of the project went smoothly, with the conversion completed within the prescribed time frame of 8 weeks, including commissioning.
The company Wilhelm Jost GmbH & Co. KG can look back on a long history: Everything started with a paving operation, more than 100 years ago. Today, Werner and Bernd Jost operate a well-run road construction company that has been in the family for multiple generations. Their diabase quarry, which Wilhelm Jost GmbH & Co. KG acquired in the 1970s, is based in Altenkirchen. They also run an asphalt mixing plant a few kilometers away, in Braunfels-Philippstein, since the 1960s
The Altenkirchen quarry primarily supplies three asphalt mixing plants (including its own) and three concrete mixing plants with the production of high-grade aggregates. Other materials are sold as a mixture to nearby clients, with some also serving their own internal demand. Metso is a turnkey supplier for the quarry, supplying the screening solution as well as the crushing equipment (LC145, Nordberg® HP3™ cone crusher, Nordberg® HP100™ cone crusher Modular and Lokotrack® LT1213S™) and related wear and spare parts.
Renewing the existing plant and solving a production bottleneck
As early as 2016, the company’s management was considering two options: construct a completely new building or, alternatively, gradually renew the existing production plant at the Diabaswerk Altenkirchen over a period of time. Large parts of the plant had been in operation since 1994 and were at the end of their economic life. In view of an impending loss of production and the limited space available, a gradual and partial renewal of the old plant was considered the best option. So, in 2018, together with Metso Germany, project planning got under way.
In addition to the renewal of the machines, another goal was to eliminate a problematic bottleneck in their high-grade chippings production in order to be able to expand the capacity of the high-demand 5/8, 8/11, 11/16 and 16/22 mm fractions.
“We are convinced that in the future the market will require even greater quantities of high-quality aggregates,” explains managing director Bernd Jost.
In 2018, Metso was awarded the contract for the detailed planning and realization of the project to convert and modernize the quarry’s fine-chippings production. The contract included the planning, delivery and assembly of three screening machines, the supply of media and a vertical impact crusher.
The existing steel construction for the high-grade chippings plant had to remain untouched as much as possible. The project kicked off with the installation of two new bucket elevators, which were renewed by Wilhelm Jost GmbH & Co. KG on their own initiative. Metso supplied a new chute and the steelwork reinforcements needed for the conversion.
Considering the limited space available, the capacity expansion of the high-grade chippings plant could only be achieved with machines from the broad Metso portfolio, which corresponded exactly to the required dimensions. In addition, the statics for all system components had to be recalculated and partially revised.
Replacing primary, secondary and tertiary screens
The first replacement machine was a single-deck screening plant, which mainly screens antifreeze material from the 0-150 mm feed material. The underflow from this screening stage goes to stock for sales or passes through a Metso HP100 secondary crusher into the high-grade chippings production. The oversize passes through the third and fourth crushing step into the Edelsplitt screening. The Metso ES203, a three-deck elliptical screen was installed as the replacement machine for the processing of the material in the Edelsplitt screening.
The screen divides the material into three fractions (8, 22 and 32 mm) over the nine square meters of screen decks. Wire cloth is used in the lower deck, and the upper decks are equipped with Trellex LS RU rubber screen panels. The time spent on maintenance has decreased with the Trellex rubber screen panels because replacements are quick to do.
Like the other screening machines, the more than 10-tonne ES203 had to be lifted through the roof at a height of 25 meters and positioned precisely. Jost GmbH chose the new ES screen because, at the given throughput, it manages the job with the smallest screening surface and thus works most effectively.
In the tertiary screening stage, a Metso CVB202 screen will be used to classify the 8/11, 11/16 mm and 16/22 mm chippings fractions. This two-deck screening machine has a screening surface similar to the ES203 and is also equipped with the Trellex LS RU rubber screen panels as well as with wire mesh on the last meter. Even with the required screening surface and the limited space available, a suitable circular motion screen could be found from the CVB series.
More powerful Barmac vertical impact crusher solves production bottleneck
In order to realize the planned capacity increase in the high-grade chippings production, it was necessary to find a more powerful vertical impact crusher – in addition to the use of more productive screening machines. The choice fell to the Barmac® B7150SE™ vertical shaft impact (VSI) crusher, which can process up to 545 t/h, depending on settings and feed material.
The Barmac now takes over in the quaternary crushing stage and with its great performance eliminates the bottleneck that previously existed. Using the Metso HP3 cone crusher in the tertiary stage, the over 45 mm material is first broken down to 0/32 mm and then processed further in the new Barmac.
Another major challenge was the adaptation of the new material drains, chutes and screen trays to the existing chutes and conveyor belts. This task was also solved by the engineering and assembly team.
The more powerful machines are transferring much higher loads onto the existing steel construction. The new Metso ES203 elliptical screening machine could therefore only be commissioned after structural reinforcements had been installed. The weight of this screening machine alone is already double that of its predecessor. A professional preparation and flawless static calculations allowed all of the machines to be installed correctly from the start.
Ensuring continued production during the project
During the renewal phase of the project and to keep production running smoothly, the company used another LT1213S mobile impact crusher and two mobile screening plants rented from Metso’s distributor Fischer-Jung, in addition to their own machines.
All in all, the planning and installation phase went smoothly, and the conversion took place within the prescribed time frame of eight weeks, including commissioning.
“Apart from the adaptation of individual screen panels and settings of the material flows in the Barmac, which is completely normal, there were no unpleasant surprises,” reported Bernd Jost.