MINING SCREENS
HAZEMAG ’ s mobile and modular screen for OCP
Moroccan phosphate mining giant OCP has a long and ongoing relationship with Germany ’ s HAZEMAG but the latest crushing and scalping unit supplied stands out in terms of innovation – it is all at once compact , modular and mobile but also capable of 3.5 Mt screening and crushing per year .
Recently , commissioning tests of the mobile crushing and screening unit at the Benguerir phosphate mine commenced . In all , 1,250 t of equipment was supplied including a 750 t main unit . It integrates equipment with new technologies such as silent screening using 15 mm disc scalpers , an innovative metal retaining wall capable of supporting 190 t class mining trucks , a five-module mobile system , and remote monitoring capability for production and maintenance indicators . The crushing system utilises a HAZEMAG HHI Horizontal Impact Crusher .
The project is a collaboration between HAZEMAG Germany , HAZEMAG Morocco , Charcomem and Sphinx , on one side and OCP plus JESA ( 50 % OCP ; 50 % Worley ) on the other . Located some 70 km north of Marrakech , Benguerir is the newest of Morocco ’ s four phosphate mining centres , having started production in 1979-80 . The mines at Benguerir and Youssoufia together make up the Gantour system , the thirdlargest phosphate mine in the world . Phosphates from Gantour are transported to Safi for processing and export .
environments . As sound dynamic behaviour is essential to ensure vibrating equipment reliability , all equipment is built to perform within strict dynamic parameters . All internal mating surfaces are machined in order to maintain stringent dimensional tolerances . In addition , the company ’ s quality assurance programme makes provision for a full 3D vibration analysis to be conducted on all equipment prior to release . This is used as a benchmark for the life of the equipment .”
All equipment is manufactured in-house by Vibramech at its 20,000 m 2 premises in Chamdor , Krugersdorp , some 35 km west of Johannesburg , South Africa . Almost every piece of equipment is tailor-made to suit a client ’ s specific requirements , from both a plant layout viewpoint and process considerations . A present staff complement of 200 control all activities from sales through to engineering and manufacturing . All equipment is designed and manufactured by Vibramech without the use of manufacturing subcontractors . “ This ensures complete control over quality and scheduling . Furthermore , its flexible and practical approach to screen design enables the client to optimise the vibrating equipment geometry to suit its specific requirements , resulting in tailor-made equipment .”
Vibrator motor and geared exciter repairs form part of Vibramech ' s service offering , with repairs conducted to OEM specifications . “ URAS vibrator motors and geared exciters are part of Vibramech ’ s key product offering , which are repaired at Vibramech ’ s factory . Vibramech has
distributed URAS vibrator motors as part of its vibrating equipment product offering since 1981 and is the exclusive URAS vibrator motor distributor for Africa and the Middle East .”
McLanahan builds on dewatering heritage
Dewatering screens were introduced by VELCO in the 1970s to dewater coal in South Africa . Unlike traditional screens used for sizing and separating , dewatering screens were designed to capture all the material on the screen deck , allowing only the excess water to pass through . In 1980 , Linatex brought dewatering screens to the United States , where they became very popular in the coal industry . A decade later , dewatering became more common practice in the aggregate industry , and dewatering screens soon found a home there as well .
Dewatering screens remove excess moisture from partially dewatered material discharged from a fine material screw washer or hydrocyclone / separator . The material is fed onto the dewatering screen ’ s steep ,
inclined surface at the feed end to achieve rapid
drainage . Two counterrotating vibratory motors throw the material upward and forward along the screen deck at high G-forces . This motion allows water to detach from the particles . The uphill slope of the screen creates a deep bed of material that allows material finer than the screen openings to be retained and the water to pass through .
Although McLanahan dewatering screens are based on the original VELCO design , McLanahan has made improvements over the years that have enhanced operation and simplified maintenance . “ McLanahan dewatering screens are built with a robust crossbeam structure that can withstand the most extreme applications yet makes the machine easy to maintain . They also feature heavy-duty screen media with full-length engagement that nearly eliminates material getting in between the urethane sections , which can lead to premature wear . McLanahan dewatering screen panels snap into place rather than pin in , which makes them easier to change out when a panel needs to be replaced .” The screens also feature longitudinal dividers on the screen deck to dewater up to three different products on the same screen at one time .
In early 2020 , McLanahan officially launched a modular , skid-mounted UltraDRY dewatering screen complete with sump and pump after numerous successful installations of skidmounted units . These screens are designed to fit under any brand of sand screw or cyclone and can be moved easily with one pick . The water that drains through the screen media is captured in the sump beneath the screen and can be recirculated back to the screw or pumped to a downstream process .
Dewatering screens typically discharge material at 8-12 % moisture , but McLanahan dewatering screens have been known to achieve as low as 7 % moisture . Removing this excess moisture from a final product ahead of stockpiling allows for quicker sale , less mess under conveyors for improved housekeeping and less water lost to waste for a more sustainable site .
McLanahan dewatering screens are built with a robust crossbeam structure that can withstand the most extreme applications
International Mining | OCTOBER 2021