Constantly above average

A new quarry has started operation in Oklahoma, USA, with mobile crushing and screening technology from Kleemann. Mining and processing were preceded by a start-up phase of just three months.

MOBIREX and MOBISCREEN in combination

MOBIREX and MOBISCREEN in combination

One of the United States‘ most valuable gypsum and anhydrite deposits is located in Longdale in the heart of Oklahoma. This is where Hoskins Gypsum set up its modern extractive operation – the Hoskins Quarry, which went into operation in 2011. The anhydrite extracted there is processed for use in road construction, agriculture and the oil industry, using crushing and screening technology from Kleemann. A combination of functionally matched mobile units ensures that output and product quality are maintained at a consistently high level. As a result, the Hoskins Quarry produced 110,000 tons of high-quality anhydrite per month only a short while after starting operation. “That‘s more than we expected but it has now become our new target,” explains Jessie Hoskins, President of Hoskins Gypsum LLC.

The process is straightforward: raw material is extracted by drilling and blasting, then picked up by a hydraulic excavator and transferred to dumper trucks which transport it to the mobile in-line Kleemann systems, where hydraulic excavators load it into the two MOBIREX MR 122 Z impact crushers. Fines and impurities are first removed from the feed material on a pre-screen. Since each impact crusher is connected to a separate mobile doubledeck screening unit, the material can be processed in a single crushing stage. The crushed anhydrite is screened via either the MOBISCREEN MS 19 Z or the smaller MOBISCREEN MS 15 Z, depending on the final grain size required. Particularly the units‘ easy operation has proved invaluable in everyday use. “Controlling the feed chute and pre-screen is easier than we thought,” says Jessie Hoskins. “All the machine operator needs is a remote control to start or stop production, increase or reduce output, entirely as required.”


The mobile crushing and screening units achieve hourly rates of up to 500 tons. “The Kleemann impact crusher‘s pre-screen is a key element for our operations,” says Jessie Hoskins. The feed material contains a very large proportion of fines which would increase wear and fuel consumption unnecessarily during the crushing process. Besides which, the fines can also be sold. Preliminary screening therefore not only improves the quality of the end product, but also makes the entire process vastly more cost-efficient. Jessie Hoskins explains: “The mobile crusher‘s fuel-efficient diesel-electric drive was another very important argument in favour of my decision to buy this machine. We need between 19 and 22 litres per hour. Such low fuel consumption is unique in this size class.”

Operating site: Hoskins Quarry in Oklahoma, USA
Partner: Hoskins Gypsum
Mined material: Gypsum and anhydrite
Machines on the job: 2 x MR 122 Z, MS 19 Z and MS 15 Z