Mining hydraulics secures the working space in longwall mining, the void in which people and machines operate. Extraction depths for raw materials such as coal keep increasing, and with growing depth come harsher conditions: extremely high temperatures and rising rock pressure. The key technology for mastering these conditions is the hydraulic shield support, which props the longwall face and advances with the extraction. As the global market leader for hydraulic power stations in coal mining, KAMAT focuses on developing and manufacturing these hydraulic systems with plunger pumps. KAMAT hydraulic power stations for underground use operate around the globe, in particular in high-performance longwalls in the USA, Australia, China, and India
What Is Mining Hydraulics?
Mining hydraulics refers to the hydraulic systems that power the shield support in underground mining. They perform two tasks: they prop the void in the extraction area (the longwall face) against the rock pressure, and they advance the supports and the armoured face conveyor as extraction progresses. The pressure medium is not hydraulic oil but a water-based HFA emulsion, supplied by high-pressure pump stations at 350 to 420 bar. Mining hydraulics is the most demanding application within water hydraulics.
Longwall mining is the most modern and most productive extraction method for stratified deposits, above all hard coal. A shearer loader cuts the coal from a face several hundred metres long. The hydraulic shield support props and secures the void in the extraction area and moves the supports and the face conveyor forward with the advance of mining.
How Does Hydraulic Shield Support Work?
Each support shield consists of hydraulic legs (cylinders) that transfer the supporting pressure into the roof, the rock above the face. The electrohydraulic support control operates the shields in a fixed sequence: release the legs, pull the shield towards the face, set the legs again, push the conveyor forward. In modern high-performance longwalls this happens within seconds along the entire face length.
The energy for these movements comes from hydraulic power stations at the face end or in the roadway. One of the central requirements is that the high-pressure pumps and pump stations deliver the required flow of hydraulic emulsion at the specified pressure, reliably and with high availability. If the emulsion supply fails, the entire longwall stands still.
Requirements Increase With Depth
Alongside ever deeper workings, growing face lengths mean that the supporting forces to be transferred into the roof keep increasing. The consequences are rising hydraulic pressures and larger cylinder diameters. Higher cutting speeds of the extraction machines also demand fast advancing of shields and conveyor, which causes high alternating loads in the hydraulic system. The pump station has to absorb these load changes and keep the pressure stable.
Why Water Hydraulics With HFA Emulsion?
Underground, the shield support runs on HFA emulsion: water with up to 5 percent additives against corrosion, bacteria, and foaming. Compared with oil hydraulics, water hydraulics offers tangible advantages underground:
- Fire-resistant: HFA consists of at least 95 percent water. Underground, where methane and coal dust are ever-present, this is a decisive safety advantage.
- Economical at large volumes: Longwall hydraulic systems contain several thousand litres of fluid. Water with additives costs a fraction of hydraulic oil and is far easier to dispose of.
- Faster control response: Water has very low compressibility and low viscosity. The support control therefore reacts faster than an oil hydraulic system, and piping can be smaller in diameter.
- Uncritical leakage: Escaping emulsion endangers neither personnel nor the environment to the degree oil does.
At the same time, this barely lubricating, corrosive medium places high demands on the pump technology. KAMAT plunger pumps are designed for continuous operation with HFA emulsion and with plain water; materials and sealing systems are matched to the medium.
KAMAT Hydraulic Power Stations for Underground Use
KAMAT supplies complete hydraulic power stations from its modular system: high-pressure mining pumps in triplex and quintuplex design with drive, control, filtration, and monitoring, mounted on frames for rails, skids, wheels, or suspended transport in the roadway.
| Parameter | Value |
|---|---|
| Operating pressure, shield support | 350 to 420 bar |
| Medium | HFA emulsion, water |
| Drive power, single pump | 132 to 800 kW |
| Station power | above 2,000 kW |
| Design | Triplex and quintuplex plunger pumps, modular system |
| Manufactured in | Witten, Germany |
Cooling and Dust Suppression
Besides supplying emulsion to the supports, KAMAT stations deliver water underground for cooling the extraction machines and for dust suppression at the shearer and the transfer points. Typical operating points are around 220 bar with flow rates above 1,600 l/min per station. Both duties are covered with pumps from the same modular system, with standardised internals and a shared spare parts stock.
Maintenance Without Lifting Gear
Service access only via the shaft, no crane at the installation site: KAMAT pumps are designed for these conditions. Seal changes are carried out without dismantling the pump head, without lifting gear, and without special tools. The pump heads are machined from forged stainless steel without coating, which eliminates flaking coatings as a typical cause of failure. Standardised internals across the pump series keep the spare parts stock small, even when several pump sizes run in the same mine. KAMAT also supports operators with commissioning, maintenance, and training on site.
Why Mining Hydraulics From KAMAT?
- Market leadership: KAMAT is the global market leader for hydraulic power stations in coal mining, with systems in the world’s major mining regions.
- One modular system for all duties: Emulsion supply, cooling, and dust suppression from the same pump series, with one sealing kit principle and one tool kit.
- Easy to maintain underground: Seal changes without a crane, without special tools, without dismantling the pump head.
- Robust materials: Pump heads made of forged stainless steel, designed for HFA emulsion and plain water.
- Made in Germany: Developed and manufactured by the family-owned company in Witten since 1974.
- Worldwide service: Installation support, commissioning, and training of operating personnel on site.
For the design of an emulsion or water supply in longwall mining, KAMAT specifies the right station configuration based on face length, support density, and target output.
| KAMAT Brochure Mining | Brochure |  |
815.4 | KB |
| Hydraulic Longwall Power Packs | Application Report | |
398.1 | KB |
Frequently Asked Questions About Mining Hydraulics
Mining hydraulics refers to the hydraulic systems that power the shield support in underground mining. They support the void in the extraction area (the longwall face) and advance the supports and face conveyor as mining progresses. The pressure medium is HFA emulsion supplied by high-pressure pump stations operating at 350 to 420 bar.
The hydraulic shield support props the roof above the extraction area and protects personnel and mining equipment. With every cut of the shearer, the shields advance hydraulically. In modern high-performance longwalls exceeding 300 metres, this movement is controlled electrohydraulically within seconds.
HFA emulsion contains at least 95% water and is therefore fire-resistant, providing a major safety advantage underground. It also offers lower fluid costs for systems containing several thousand litres and responds faster than oil hydraulics because of water's low compressibility.
HFA is a fire-resistant hydraulic fluid consisting of water with up to 5% additives, including corrosion inhibitors, bactericides, and anti-foaming agents. KAMAT plunger pumps are specifically designed to operate with this low-lubricity fluid as well as with plain water.
Typical operating pressures are 350 to 420 bar for shield support and around 220 bar for cooling and dust suppression with flow rates exceeding 1,600 l/min per station. KAMAT single pumps cover 132 to 800 kW, complete hydraulic stations exceed 2,000 kW, and the overall product range extends to 4,000 bar, 3,000 kW, and 10,000 l/min.
Since underground service access is often only possible via the shaft and lifting equipment is rarely available, KAMAT pumps are designed for easy maintenance. Seals can be replaced without removing the pump head, without a crane, and without special tools. Standardized internal components also reduce spare parts inventory.
KAMAT is the global market leader for hydraulic power stations in coal mining. Its systems operate in high-performance longwalls in the USA, Australia, China, and India. One recent example is a 300-metre-long longwall at a depth of 500 metres in India. All systems are manufactured in Witten, Germany.
As mining depth increases, rock pressure and temperature rise while longwall faces become longer. Higher support forces are therefore required, demanding increased hydraulic pressure, larger cylinder diameters, and pump stations capable of maintaining reliable flow rates even under rapidly changing loads.
