Constantly above average
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 plants 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 first extracted by drilling and blasting, then picked up by a hydraulic excavator and transferred to dumper trucks which transport it to the linked 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 prescreen. Since each impact crusher is connected to a separate mobile double-deck screening plant, 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 vibrating feeder and prescreen 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 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."
Jessie Hoskins, President of Hoskins Gypsum LLC
Prescreen ensures higher cost efficiency and product quality
The mobile crushing and screening units achieve hourly rates of up to 500 tons. "The Kleemann impact crusher's prescreen 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. Prescreening therefore not only improves the quality of the final product, but also makes the entire process vastly more cost-efficient. Jessie Hoskins adds: "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."