WATER MANAGEMENT
Water wisdom
Huge filter presses such as FLSmidth ' s Colossal filter represent one of the only viable dewatering options for the largest mines that want to move away from wet TSFs
In this article on water management , Paul Moore looks at a broad range of topics from compliance to water treatment , dewatering & TSF water
Looking first at water treatment solutions , these are customised to the unique needs of each mining project and are tailored based on scale , chemistry , already existing infrastructure , what needs to be removed and of course available technologies . Often projects require a collaborative approach to achieve long term goals .
WEC Projects , in conjunction with its partner , Multotec , recently designed and custom engineered a wastewater treatment plant for a gold mine in Mali , West Africa . The plant , used to remove arsenic from the mine ’ s wastewater stream , incorporates a modular design which simplifies the logistics and reduces the costs of transport and installation .
The international mine operator is a client of Multotec , the South African engineering company specialising in mineral processing plant design and installation . The company approached WEC Projects , an EPC contractor in the water and wastewater treatment industry , to jointly develop a customised solution to remove toxic arsenic from the mine ’ s wastewater . A multi-stage removal system was required to meet the strict standards for the mine ’ s discharge . However , the system also required a modular design which would facilitate the transportation , installation and commissioning of the plant .
Says Wayne Taljaard , Managing Director of WEC Projects : “ The mining industry in Africa presents some very unique challenges , not the least of which are the remote locations of many of the mines and the difficulties experienced in getting staff and equipment to sites where road , power and water infrastructure is often lacking , hence the requirement by Multotec for a modular solution that would allow for rapid transport to site and to simplify its installation and commissioning . The COVID-19 pandemic added to the difficulties for us and the client , causing delays that reduced the time frame for delivery .” In the treatment process , the mine ’ s wastewater undergoes primary solid / water separation using coagulation and flocculation and the primary clarifier . From there it enters a two-stage chemical precipitation and secondary clarification process to reduce the arsenic levels . The final stage sees the sludge undergo dewatering before disposal . The treated water , although not potable , is then reused by the mine for process applications .
The plant has a processing capacity of 150 m 3 / h and is capable of reducing the arsenic levels from around 13 mg per litre to less than 0.1 mg per litre . Taljaard adds : “ The project incorporates a number of unique features in addition to its modular design , including nine custom-designed , proprietary lamella clarifiers and a multi-stage arsenic removal process capable of treating the wastewater to the mine ’ s discharge standards . WEC Projects has completed a number of water and wastewater treatment projects throughout Africa . Our ability to provide a customised and modular solution for Multotec underscores our ability as a major player in the industry both in South Africa as well as across the continent .”
In Australia , Osmoflo , in partnership with prime contractor Aerison , recently announced the award for a significant new water treatment system at the Roy Hill Mine . The 40 ML / d capacity ultrafiltration and seawater reverse osmosis ( UF-SWRO ) plant will be one of the largest facilities Osmoflo has delivered globally over its 30-year history and will also constitute one of the largest non-municipal SWRO facilities built in Australia to date .
Aerison is a multi-discipline company providing engineering and design , construction and maintenance services to the mineral processing , energy and infrastructure sectors .
Aerison has a strong presence offering engineered solutions to reduce the impact of industry on the environment , and through its partnership with Osmoflo , the project will deliver superior water treatment infrastructure to support the mine site operations .
This win continues Osmoflo ’ s involvement with the Roy Hill mine , the world-class iron ore mining operation near Newman in Western Australia . Osmoflo has been part of the Roy Hill mine success story for several years having successfully completed delivery of the current 20 MLD Brackish-Water Reverse Osmosis ( WTP1 ) plant in mid-2019 and providing reliable operations services under a ‘ full risk ’ 10 + 10 year O & M contract since .
Osmoflo developed a robust and innovative solution , drawing upon extensive operational and process experience at the site . The team maximised the use of the existing WTP1 asset , reducing the capital intensity of the facility expansion . As lead EPC contractor , Aerison brought its in-house engineering and construction capabilities spanning civil , mechanical and electrical disciplines , and long history delivering complex projects of scale to asset owners in the Pilbara region of WA , providing an ideal partnership with Osmoflo .
Osmoflo ’ s Chief Executive Officer , Takayuki Inoue , observed : “ We are pleased to again be working with Roy Hill to provide them with a robust and reliable water treatment solution to meet their water needs for the foreseeable future . The complementary knowledge , experience and capabilities of both Aerison and Osmoflo enabled our team to respond to Roy Hill Mine ’ s competitive ECI process with a superior technical solution , competitively priced and delivered under a very challenging schedule and to meet Roy Hill ’ s strict technical requirements and specifications .”
Paul Laybourne , Roy Hill ’ s Director of Projects stated : “ The Osmoflo-Aerison team presented a robust , efficient , value-for-money water treatment solution that will provide our mine operations team with maximum flexibility and water availability at all times . Their solution also provided a high level of integration and ongoing utilisation of our existing BWRO / WTP1 plant .” The plant is due to be commissioned in the first quarter of 2023 .
Advanced water dispatch at Teck ’ s Elk Valley mines
Water management is key to the sustained future of Teck ’ s coal mining operations in the Elk Valley . Since 2013 , Teck has been working with local
16 International Mining | MARCH 2022