Margaux Red Capital and its wholly-owned subsidiary Sigma Lithium Resources have made an important step towards completing the feasibility study of Sigma’s foothold deposit at its Grota do Cirilo Property in Minas Gerais state, Brazil. Sigma has finalized the environmental licensing process for its Dense Media Separation (DMS) pilot plant and expects to complete its construction in June 2018.
The pilot plant flowsheet was designed after Sigma conducted successful metallurgical tests for over eight months, producing high-quality battery-grade lithium spodumene concentrate above 6% Li2O at SGS laboratories in Canada and Brazil.
The pilot plant will have a capacity to produce up to 12,000 t/y of lithium spodumene concentrate at the rate of 10 t/h. The pilot plant will consist of a two-stage crushing circuit with a capacity of 30 t/h, a magnetic separation unit and a DMS unit, which will produce a coarse concentrate of +4mm to -15mm size fraction. Sigma is currently conducting tests of ore sorter technology, which will be later added to the pilot plant.
Sigma’s premium lithium spodumene concentrate samples produced by the plant will be sent to prospective clients for validation and certification purposes. “The pilot plant is an important milestone on the path to becoming a fully operational world-class lithium producer by 2020. The metallurgic tests to date have produced a coarse lithium spodumene concentrate above 6% Li2O, using simple DMS processing technology, validating the superior quality of our lithium,” says CEO Calvyn Gardner.
“With the advent of electric cars, most of the growth in lithium demand is coming from the chemical producers of lithium hydroxide supplying the battery cathode industry. Sigma is uniquely positioned to cater to this growing demand, due to our ability to produce in-spec 6% lithium concentrate from our high-grade high-purity spodumene ore. Lithium is not rare, but Sigma’s differentiation comes from the high quality and purity of our foothold deposit at 1.56% average grade of lithium for our estimated Measured and Indicated Resources,” he adds.
Brazil-based Sigma President Itamar Resende says: “The superior metallurgy of our spodumene concentrate was demonstrated by the excellent 73% recoveries obtained, using just the one-stage DMS, for ore sizes crushed at both 6.5 and 9.5mm. As a result, Sigma can build a low-capex DMS commercial processing plant with superior productivity and recoveries. Flotation tests of the middlings from the DMS also produced a fine concentrate with Li2O above 6% with exceptional recoveries of 86%.”
Sigma’s larger-size spodumene concentrate, especially at 9.5mm particles, is seen to be a premium product because it increases the recovery rates achieved by chemical producers of lithium hydroxide in their calcination process within their kilns.
Itamar adds: “The superior quality of our spodumene lithium concentrate provides Sigma with a competitive advantage when marketing to customers in the chemical industry as they experience excellent recovery rates and higher productivity. As producers of battery grade lithium hydroxide can take up to 12 months to validate a new supplier, our goal is to be qualified well before we start production, which we are targeting to be by the end of 2019.”
Sigma plans to implement advanced green and sustainable mining processes at its Minas Gerais operation. The electricity on site is generated by a clean hydroelectric power plant and Sigma will recycle 100% of the water utilized in the plant, while the waste system will stack the mining tailings in dry piles, hence avoiding tailings dams.
Sigma has 28 mineral rights in four properties spread over 188 km2 and 18,887 ha -with over 200 lithium bearing pegmatites and 11 former historical lithium mines. The Grota do Cirilo property, Sigma’s primary focus, includes 10 mining concessions (mining production authorizations) and is currently undergoing a 20,000 m drilling campaign for resource expansion.
Sigma has a NI 43-101 technical report on the Grota do Cicilo property prepared by SGS Canada-Geostat, which includes estimated Measured and Indicated resources of approximately 12,900,000 t for its main deposit (8,502,000 t Measured and 4,385,000 t Indicated), with a high average grade of 1.56% (for approximately 5,000,000 t of LCE). The technical report also includes estimated inferred resources of 608,348 t and further notes the potential for significant resource expansion.