Tag Archives: quartz

COREM, Steinert ore sorting tests present opportunities for Cartier at Chimo gold project

Cartier Resources says ore sorting tests carried out by COREM and Steinert US on mineralised samples from the Chimo Mine property, in Quebec, Canada, have indicated gold grades could increase substantially with the use of the pre-concentration technology.

Gold from Chimo is present in two types of mineralised facies: i) quartz veins with coarse visible gold grains having an affinity for the gravity concentration of gold at the mill and ii) zones of silica-rich mafic rocks associated with non-refractory arsenopyrite having an affinity for the flotation of a concentrate of arsenopyrite for gold recovery at the mill.

To perform the sorting tests, rocks representative of the two mineralised facies, made up of the following six mineralogical facies, were first selected for static recognition of each of the facies by the sensors of the sorter:

  • Gold-bearing quartz veins;
  • Gold-bearing silica;
  • High grade gold-bearing arsenopyrite;
  • Medium grade gold-bearing arsenopyrite;
  • Low grade gold-bearing arsenopyrite; and
  • Mafic waste rock.

The detection sensors of the industrial sorter at COREM in Quebec, Canada, were the RGB camera using the optical properties of reflection, brightness and transparency to locate quartz and silica and the X-ray Transmission sensor using the volumetric property of atomic density to locate arsenopyrite. The two sensors adequately recognised the six mineralogical facies associated with the mineralisation, with dynamic calibration tests of the sorter with the moving conveyor making it possible to sort, one at a time, 2 kg samples of each of the facies, Cartier said.

The results of this first test at COREM showed the first three sorts (on a total of eight sorts) concentrated 99.1% of the gold contained in 44.4% by mass of material mass for a grade of 56.3 g/t Au, representing a percentage increase of 223% in gold content over sorter feed. The reject, representing 0.9% by mass of material, contained only 0.4 g/t Au.

The sorter was then ready to perform sorting tests on the 105.7 kg production sample, representative of the mineralised facies at an average grade of 2.16 g/t Au. This content was obtained by including 20% by mass of material with zero grade of gold, simulating dilution in the stopes. COREM’s sorting plan separated 53.9% by mass of the material in the form of a preconcentrate at an average grade of 3.68 g/t Au, representing an increase of 170% in the gold grade compared with the sorter feed. The waste disposal, separated from the mineralisation, represented 46.1% by mass of material at an average grade of 0.38 g/t Au.

Sorting tests carried out with Steinert in Kentucky using a Steinert KSS FLI XT machine with XRT, colour, laser, and induction sensors yielded comparable results.

A 80.69 kg production sample, representative of the mineralised facies at an average grade of 2.13 g/t Au, to which 20% by mass of material at zero grade of gold was added mathematically, representing the dilution in the workings, was used for testing. The new calculated diluted grade was 1.55 g/t Au.

Calculation of the results revealed that 51% by mass of the dilute grade material could be separated as a preconcentrate at an average grade of 2.72 g/t Au, representing a 175% increase in gold grade compared with the sorter feed. The waste disposal, which would be separated from the mineralisation, would represent 49% by mass of material at an average grade of 0.36 g/t Au.

Sorting tests with COREM were carried out following these tests to validate that the 20% of dilution material at zero grade of gold, mathematically added, could physically be effectively separated by the sorter, Cartier said.

The sorting tests carried out by both COREM and Steinert US were comparable, with these results providing prospects for increasing the value of the resources with ore sorting technology.

The objective of the industrial sorting of the mineralisation is to increase the grade of the preconcentrated material preceding the milling operations, which allows an increase in the recovery rate at the mill, reduces transport costs to the mill, reduces milling costs, reduces the costs of environmental restoration of mine tailings, and reduces the environmental footprint of mine tailings and, consequently, increases the social acceptability of the mining project, Cartier said.

The most recent resource estimate from Chimo included 6.6 Mt at an average grade of 3.21 g/t Au for a total of 684,000 oz of gold in the indicated category and 15.2 Mt at an average grade of 2.77 g/t Au for a total of 1.36 Moz of gold in the inferred category.

Piedmont enlists Primero and Marshall Miller for lithium concentrate DFS

Piedmont Lithium has awarded the definitive feasibility study (DFS) of its planned spodumene concentrate operations in North Carolina, USA, to a combined team including Primero Group and Marshall Miller & Associates.

Marshall Miller is to lead quarry design activities, while Primero will advance the concentrator design, infrastructure design, and be responsible for overall study management, Piedmont said.

The study will target production of 160,000 t/y of 6% Li2O spodumene concentrate, as well as co-products including quartz and feldspar. It will include the results of the pilot test work currently ongoing at SGS Canada, which will involve “dense medium and flotation” pilot work.

Piedmont expects to complete the study on its namesake project in mid-2021 and pursue an investment decision for the concentrate operations shortly after.

At the same time, Piedmont says it is looking into developing an integrated lithium hydroxide business in North Carolina, with a planned lithium chemical plant DFS to commence in the March quarter.

Earlier in 2020, Piedmont entered a memorandum of understanding with Primero Group related to delivering the planned spodumene concentrator at the Piedmont lithium project. The two have partnered since early 2018, with Primero having been the lead engineering consultant for Piedmont’s scoping studies, concentrator design, and metallurgical test work management.

Piedmont has engaged Marshall Miller, based in Bluefield, Virginia, since 2018 to advance mine design, permitting activities, survey, geotechnical study, waste rock and tailings storage design, and other engineering support services.

Turkey’s Mikroman ups product quality, throughput with TOMRA ore sorters

Turkish quartz miner, Mikroman has been able to both improve product quality and increase capacity at its three processing plants in the country thanks to the installation of four TOMRA Sorting Solutions high-capacity sensor-based sorting systems, the technology company said.

Mikroman mines quartz from its open-pit operations in Turkey, with the company running its own mineral processing plants for crushing, washing and sorting the raw materials.

In 2018, the company installed a TOMRA PRO Secondary LASER sorting machine in two of its three plants, in Muğla and Aydin Provinces. The third plant, in Usak Province, invested in a LASER sorter plus a COLOR sorter, according to TOMRA.

TOMRA says: “In addition to being the most efficient way to sort particles, sorting machines deliver a wide range of commercial advantages to industrial mineral sorting businesses. These include a decrease in mining and haulage costs; reductions in energy and water consumption; improvements in quality and productivity; and increases in recovery.”

The company added: “Sensor-based sorters also make it possible to significantly increase the lifetime of a mining operation.”

TOMRA’s Area Sales Manager, Jens-Michael Bergmann, said TOMRA’s COLOR sorting machines employ a high-resolution camera that recognises materials based on their color. “Rocks with surficial and visible contamination are detected and sorted out, resulting in better recovery rates and higher quality than is possible with manual sorting,” he said.

“Our unique multi-channel LASER sorter delivers even greater benefits for Mikroman in achieving the highest purity levels and maximum profits. The scattering effect of multiple laser beams distinguishes a rock containing quartz from its identically coloured neighbor. Under the laser beam, a pure or non-contaminated quartz rock registers as a glow crystal, whereas similar looking rocks with no quartz content remain dark, without any visible scattering.”

Mikroman combined these two technologies for best results and recovery, according to TOMRA.

Of all three Mikroman processing plants, the one in Usak Province demands the most precise mineral sorting. Before sorting, the feed material is screened by size, with the 40-100 mm stones treated with a higher priority and stones measuring 20-40 mm in size sent down the sorting line in a separate batch. Here, the combination of a TOMRA COLOR sorter and TOMRA LASER sorter is used to differentiate products according to four predetermined qualities. These are:

  • White and light grey quartz, with low iron oxide content, for use as artificial stones (A);
  • Grey and yellow quartz, for use by the glass industry (B);
  • Coloured quartz, for ferrosilicon used by the metallurgical sector (C), and;
  • Coloured gravel (D), also for ferrosilicon, currently goes with the waste.

After crushing and washing (through a trommel screen), Mikroman’s sorting process consists of four key steps. In the first step, minerals are screened by size, with only stones measuring 40-100 mm going through to the next stage.

In the second step, the LASER machine sorts out the waste and coloured gravel from the quartz pieces at about 70 t/h capacity. In the third stage, the remaining minerals are sorted into two streams: one for colored quartz; the other for the white and light grey quartz, and the grey and yellow quartz. Finally, these two streams are hand-sorted into product types, with some further removal of remaining gravel and waste.

“These precise distinctions, resulting in higher product quality, were not possible before the acquisition of the TOMRA machines,” TOMRA said, adding that its service team worked on-site with Mikroman, as it does with all customers, to optimise the performance of the machines.

Nazmi Çetin, Mine and plant Manager at Mikroman, said: “Before having TOMRA sorters, we were worried about quality and low capacity, but now we have achieved the desired quality standard and we have seen a decrease in waste, which means productivity has increased. The system design is quite successful and the TOMRA service team are good at their job.”