Potash is generally used to describe potassium fertilizers that are used in agriculture. In addition to nitrogen and phosphate, potassium is one of the most important nutrients and, among other things, indispensable for the productive, healthy growth of plants - and thus for a better supply of food to the growing world population. As an element occurring in nature, potassium cannot be produced synthetically and is therefore predominantly extracted in solid form in conventional mining in natural underground potash deposits. The crude salt mined by blasting or cutting at a depth of several hundred metres is extracted via vertical shafts and further processed in above-ground factory facilities.

In gigantic boiling pans evaporated

All the world's major solid potash deposits are of marine origin, formed by the evaporation of seawater since the Cambrian around 550 million years ago. As a result of evaporation, the salt concentration of the water in the inland seas increased. The dissolved salts crystallized and deposited. In the course of millions of years this process was repeated, so that rock salt layers with a thickness of several hundred metres and potash seams several metres thick were formed on top of each other. In contrast to the chloride type of potash deposits customary worldwide, German deposits belong to the special sulphate type, characterised by additional magnesium and potassium sulphate minerals in crude salt.

Photo: Max Bögl Group

Environmentally friendly stockpiling of residual salts

On the basis of this special composition of raw materials, K+S KALI GmbH, the fourth largest potash producer in the world and Europe's leading supplier, offers a broad range of standard products and high-quality specialities for agricultural and industrial applications that no other potash producer in the world possesses in this diversity. At the Werra potash plant in Hattorf alone, about 19 million tonnes of crude salt are extracted annually for the production of mineral fertilizers, pharmaceutical salts and industrial products. When raw materials are processed, production residues, whether solid or liquid, cannot be avoided despite technically advanced processes. Potash production is almost exclusively rock salt, which is not suitable for economic use. These residues must be stockpiled with the greatest possible consideration for environmental requirements, as the rock salt is washed out by precipitation and can pollute soils, groundwater and surface waters in the vicinity of the stockpile without the corresponding catchment and disposal measures.

Photo: Max Bögl Group

Intensive preliminary work guarantees order profit

As the permit to operate the old tailings pile expires in a few years' time and absorption capacities are almost exhausted, the so-called ESTA tailings pile at the Hattorf site must be expanded in order to further secure and promote potash mining. K+S KALI GmbH commissioned Max Bögl's supply and disposal department with the implementation of the major project to expand the tailings pile. In recent years, Max Bögl has developed more and more from a pure construction service company into a service provider of complete solutions. The foundation stone for this order success had already been laid weeks earlier by the specialist department when a catalogue of services worked out down to the smallest detail could be worked out and presented to the client in intensive basic work by the core bidding team from various specialist departments.

Photo: Max Bögl Group

Complex mixing recipe for base sealing

The challenge for the project "Dump extension BA A1" on the approx. 60 ha large area was the execution of a 160,000 m² base waterproofing in a record construction time of just eight months. With the start of construction in April 2018, a total of around 500,000 tonnes of bulk material - including 250,000 tonnes of sealing layer and 150,000 tonnes of filter layer - had to be installed during this tight period. In addition to the protective fleece, drainage layer, separating fleece and weather protection components, the most important component of the applied sealing system was the mineral seal consisting of two recipes. Based on the principles of the Landfill Ordinance, the formulation was further improved in close consultation with the client and the Kassel Regional Council and approved by all responsible testing bodies after trial field construction had been completed. In order to guarantee the required quality and quantities on site, the mineral seal was produced on site in a separate mixing plant and installed in two layers with the aid of a paver and feeder.

"The Max Bögl Group and I personally are very proud of our young, competent execution team in the large-scale project at K + S in Hattorf. The average age of our polishers / young construction managers involved in the project is just 27.66 years!"
Ingmar Lepiors, Head of Civil Engineering Frankfurt

Success through optimized process flows

In order to be able to complete the services to be rendered in the required quality despite the tight schedule, the site team headed by project manager Ingmar Lepiors relied on proven methods and tools. Lean management, standardized project management, CIP and maxpoint were used - a special information board with the most important project information that is used on all construction sites of the Max Bögl Group. Thanks to these working aids and smooth communication between the construction site team, the delivery, goods and traffic flows could be managed throughout the entire construction process without any loss of quality or performance. At the end of October 2018, the specialists from the Supply and Disposal Department reported the completion of just over 100,000 m² of sealing area to the client. By reaching this milestone, operational safety at the Hattorf site could be guaranteed for further time.

Photo: Max Bögl Group

Follow-up order with high safety requirements

Following on from this success, in January 2019 the project team received a further and at the same time extraordinary order: the construction of the pilot polder basin for collecting precipitation on the plateau of the 220 m high tailings pile. After relocation and installation of 30,000 tonnes of fresh salt according to profile, a waterproofing system including 1,600 m drainage pipe and leachate control system must be installed and secured with paving stone pallets to protect against wind suction. Due to the altitude, the extreme wind and weather conditions and working in and with the residual salt, very high occupational safety measures are required. The "Hägglund" armoured troop transport vehicle, which is also used by the mountain troops, is also used for chain-based operations on the dump plateau.