Qinghai Salt Lake Group Stock Company (QSLG) is a diversified state-owned enterprise whose business is founded on access to extensive chloride-based mineral resources present in the Qarhan salt lake, located approximately 40 kilometres northeast of Golmud in the province of Qinghai. The region has abundant energy resources in the form of both natural gas from the Qaidam basin and hydropower from the Xining area. Coal, limestone and other important raw materials may also be found in the vicinity of the QSLG site.
Already China’s largest potash producer, QSLG recognized the economic potential of using the magnesium chloride brine by-product from the potash process as a raw material for the production of commercial magnesium metal and alloys. Importantly, QSLG’s raw material is a chloride, so that chlorine gas is a by-product from the magnesium production process. This availability of chlorine inspired QSLG to develop a synergistic integrated flow sheet for an industrial complex, the heart of which would be an electrolytic magnesium smelter.
The proposed industrial complex includes eight process plants as well as a utilities facility and produces saleable products of magnesium and magnesium alloys, polyvinyl chloride and polypropylene, calcium chloride and soda ash, the most economically important of these being the magnesium metal products and polyvinyl chloride (PVC). This industrial complex is known as the QSLG Phase 3 expansion and it is envisioned that a further expansion (Phase 4) of the entire complex will follow the successful start-up of Phase 3.
The technology for the electrolytic production of magnesium was licensed by QSLG from Norsk Hydro following their exit from the magnesium industry and the closure of their Bécancour, Québec, Canada smelter in 2006. As Norsk Hydro had withdrawn from the industry, QSLG was in need of process and engineering support from a suitably experienced engineering partner and awarded the basic engineering project to Hatch.
The Norsk Hydro process technology was successfully operated in Bécancour, Canada for some 18 years (1989-2006) but needed to be adapted to the conditions of the Qinghai project site and feedstock. Unlike the proposed Qinghai project, Bécancour used magnesite (MgCO3) as feedstock and the Bécancour plant was built at sea level and designed to produce only 50,000 tpa of magnesium whereas the Qinghai smelter aims to produce 100,000 tonnes per annum (tpa). These three factors necessitated substantial design development and reconfiguration of the process and facilities installed at Bécancour.
The technical, economic and sustainability fundamentals of the Qinghai magnesium smelter project are strong and include the following key factors:
- Uses proven Norsk Hydro process technology
- Abundant solar energy available for brine concentration Use of chloride feedstock avoids CO2 emissions
- Use of hydropower for smelting substantially reduces CO2 emissions
- Chlorine gas by-product enables synergistic production of PVC improving economic viability
Hatch performed basic engineering for the proposed 100,000-tpa primary magnesium plant. However, because of the complex impacts associated with the different site conditions at Qinghai and the requirement for expansion, Hatch needed to perform a substantial amount of process engineering and development. In addition to the basic engineering scope QSLG requested that Hatch develop a new improved fluid bed air dryer design to overcome known problems with the previously used Norsk Hydro design.
QSLG has since engaged Hatch to continue with detailed process technology design and support. QSLG has separately awarded Hatch with larger contracts for furnace technology and engineering design associated with adjacent process plants that are part of this same integrated facility.
- The project was delivered on time and on budget
- Met unforeseen key process design challenges without exceeding budget
Basic engineering phase established key hazards and proposed mitigations to be carried forward into detailed engineering and implementation phases.
