Tag Archives: TOMRA Sorting Solutions

Rafaella considers processing options after positive TOMRA XRT ore sorting tests

Sensor-based ore sorting test work from TOMRA Sorting Solutions has shown the potential for lowering the planned capital expenditure and operating costs associated with developing the Santa Comba tungsten-tin project in Galicia, Spain, project owner Rafaella Resources has reported.

The “exceptional” ore sorting results showed a 50% rejection of un-mineralised rock and an approximate doubling of feed grade, which would significantly lower the planned process capex and opex, and enhance process efficiency through a simpler process flowsheet, the company said. The 50% cut in process tonnage also reduces the project’s environmental impact, with a far lower volume of waste generated, lower energy consumption per unit of metal produced and reduced water consumption.

The “Grade Recovery Curve” showed the potential for over 90% tungsten recovery with an increased yield of up to 55% of feed mass, it added, while testing of the low-grade ores showed viable recovery from over 2 Mt of mineralisation not currently factored into the project’s economics.

The program tested two bulk samples selected from assayed drill core crushed to two size groups: +8 mm to -20mm and +20 mm to -40 mm. Sample No. 40 was circa-1,100 kg of average grade ore at 0.15% WO3, while Sample No. 41 was circa-250 kg of low-grade ore at 0.05% WO3.

TOMRA’s conclusion in its report was that “the results from this test work were positive for both sizes and samples. Significant upgrades of WO3, as well as high recoveries, were achieved in all test runs for sample ‘40’ using X-ray Transmission (XRT), while leaving rather low grades for WO3 in the waste fraction. A calculation has shown that a 90% recovery of tungsten can be possible at a waste removal of more than 50%.

“The low-grade sample ’41’ could be upgraded by a factor of 1.7 to 3. For further calculations, a waste grade between 0.025 and 0.030 is achievable.”

The success of the XRT sorting tests allows several mining and process options, Rafaella says, including:

  • Simplification of the process;
  • Bulk ore zone mining to reduce operational costs and maximise ore recovery;
  • In-pit sorting and conveying;
  • Bulk underground mining and sorting of wider ore zones using larger and longer stopes;
  • Separate sorting of sub-grade mineralisation; and
  • Sorting of satellite deposit ores prior to hauling to the process plant.

TOMRA estimates a throughput of 1 Mt/y of feed ore and circa-500,000 t/y of pre-concentrate would require two XRT units.

Rafaella’s Managing Director, Steven Turner, said the results from the ore sorting test work have exceeded the company’s expectations.

“The clear discrimination between ore-bearing rock and low grade or barren rock has delivered high recoveries and yields allowing for a simpler process plant,” he said. “The benefits of this simplification will be significant once the metallurgical studies are completed. These results are now being fed into the feasibility study that is in the final stages of completion.

“The company looks forward to providing the market with these exciting updates on the fast tracking of its flagship project over the coming weeks.”

Santa Comba is a brownfield project with a 5.1 Mt JORC 2012 compliant near-surface inferred resource at 0.203% WO3 and 0.014% Sn and an underground inferred resource of 234,000 t at 0.95% WO3 and 0.28% Sn.

TOMRA’s SRC ties to open new North America ore sorting markets

TOMRA Sorting Solutions is gearing up for major sensor-based ore sorting orders from the North America mining market after signing a co-operation agreement with the Saskatchewan Research Council (SRC).

The company has won mining work across the globe over the last five or so years, moving from Africa diamond operations to a phosphate mine in Saudia Arabia – its largest installation to date (pictured) – to tin in South America and gold in Australia.

One of its more significant regional wins came in Canada, where it recently received a purchase order from Vital Metals’s Cheetah subsidiary to supply COM Tertiary X-ray Transmission (XRT) 1220/B ore sorting equipment to the Nechalacho rare earth project, in the Northwest Territories.

In announcing the order in January, Vital Metals said: “The ore sorting test work highlighted that the Nechalacho rare earth oxide (REO) project is one of the few and the first REO project to successfully use ore sorting to produce a high grade plus-35% REO concentrate without the use of reagents and water. This will substantially reduce the cost and the lead time to bring the Nechalacho REO project into production.”

Harold Cline, Area Sales Manager, Mining, TOMRA Sorting, said this win was significant as it was the first contract the company had sealed in North America following the agreement with the SRC.

SRC is now offering TOMRA clients sensor-based ore sorting process development work, testing and piloting as part of its full suite of SRC Mining and Energy services. The SRC also plans to expand these services further with the creation of the SRC Minerals Liberation Centre.

Up until recently, TOMRA had to send material from North America mining operations back to its test centre in Germany. While the TOMRA facilities in Europe are world-class, Cline said, having a location in North America could prove decisive when it comes to converting enquiries from miners to contracts.

“SRC was able to provide results to Cheetah in just four weeks,” he told IM on the side lines of the recent SME MineXchange Conference and Expo in Phoenix, Arizona.

This testing turnaround time could help TOMRA grow its mining sales in North America at a time when the region’s gold, industrial minerals, copper and lead-zinc mines are looking into sensor-based ore sorting solutions, according to Cline.

Vista Gold Mt Todd PFS points towards use of ore sorting, fine grinding

Following extensive metallurgic test work carried out over the past year, Vista Gold looks like it has settled on a flowsheet for its Mt Todd gold project in the Northern Territory of Australia that includes ore sorting and the selection of the FLSmidth VXP mill as the preferred fine-grinding mill.

The company detailed this in an updated prefeasibility study (PFS) for the project, which factored in the results of metallurgical optimisation test work, a redesign of the fine grinding circuit, construction and ramp-up schedule changes and a comprehensive review of all aspects of the project.

The process improvements resulted in improved projected gold recovery and increased estimated gold production at Mt Todd, Vista Gold said.

According to the PFS, a 50,000 t/d operation at Mt Todd could see the operation produce 413,400 oz/y of gold over the 13-year mine life at average all-in sustaining costs of $746/oz.

The estimated initial capital requirement came in at $826 million, with the project offering an after-tax net present value (5% discount) of $823 million at a $1,350/oz gold price and a $0.70=A$1.00 exchange rate.

In the company’s metallurgy, processing and infrastructure section, it detailed the processing side of Mt Todd, saying that recent metallurgic test programs had confirmed the efficiency of ore sorting across a broad range of head grades and the natural concentration of gold in the screen undersize material prior to sorting. The company carried out such test work at TOMRA Sorting Solutions in Germany, where two-stage (X-ray Transmission and laser) sorting tests were completed using production-sized and commercially available equipment.

It also said such test work had confirmed the efficiency of fine grinding and improved gold leach recoveries at an 80% passing grind size of 40 microns, in addition to the selection of the FLSmidth VXP mill as the preferred fine-grinding mill.

The company previously sent samples to Core Metallurgy Pty to obtain fine grinding data simulating grinding in the horizontal IsaMill and to the FLSmidth Minerals Testing and Research Center to obtain data simulating grinding in the vertical VXP Mill.