Tag Archives: quartz

Piedmont looks at IPCC, Metso Outotec alkaline pressure leach for lithium project

Piedmont Lithium’s plan to build out an integrated lithium hydroxide business from a base in North Carolina, USA, has advanced with the release of a scoping study that, it says, confirms that Carolina Lithium will be one of the world’s largest and lowest-cost producers of lithium hydroxide with a “superior” sustainability footprint.

Piedmont Carolina Lithium contemplates a single, integrated site, comprising quarrying, spodumene concentration, by-products processing, and spodumene conversion to lithium hydroxide at its site in Gaston County. There are currently no such integrated sites operating anywhere in the world, with the company saying the economic and environmental advantages of this strategy are compelling.

The latest study outlined a production target of around 4.96 Mt of 6% Li2O spodumene concentrate (SC6), averaging approximately 248,000 t/y of SC6 over the 20-year mine life. This equates to an average of 1.95 Mt/y of ore processed, totalling some 37.4 Mt of run-of-mine ore at an average grade of 1.09% Li2O (undiluted) over the 20-year mine life.

Of the total production target of 4.96 Mt of SC6, some 1.19 Mt will be sold to third parties during the operational life and approximately 3.77 Mt will be supplied to Piedmont’s chemical plant operations for conversion into lithium hydroxide. This results in a total production target of about 582,000 t of lithium hydroxide, averaging approximately 29,095 t/y of lithium hydroxide over 20 years, the company said. The study also assumes production targets of 4.83 Mt of quartz concentrate, 7.51 Mt of feldspar concentrate, and 1.34 Mt of mica concentrate over the life of operations.

Piedmont envisages a total initial capital cost of $838.6 million for the project and an after-tax net present value (8% discount) of $1.92 billion.

While still very much preliminary, the flowsheet and mining process for this planned operation is of interest to any lithium developer looking for a ‘sustainable’ mining footprint.

The company currently envisages using a Metso Outotec alkaline pressure leach process as part of its plan. This will reduce emissions, eliminate sulphuric acid roasting and reduce solid waste, it said.

At the same time, in-pit crushing and conveyor systems are on the agenda, eliminating mining trucks in the study to reduce fossil fuel consumption.

Piedmont has also been working with a solar developer to build and operate a solar farm on Piedmont property capable of producing electricity to supply up to 100% of Piedmont needs.

The company will also co-locate all operations on the same proposed site in Gaston County to minimise any transit and allow unused by-product streams to be repurposed for site redevelopment, it said. This adds up, Piedmont says, to highly efficient land and water use compared with South American lithium brine production.

Keith D Phillips, President and Chief Executive Officer of Piedmont, said: “We are exceedingly pleased with the results of our updated scoping study. The economics of our project continue to impress, but I am particularly proud of the project’s sustainability profile.

“As we move forward to complete a definitive feasibility study for Carolina Lithium later in 2021, Piedmont has engaged Evercore and JPMorgan as financial advisors to evaluate potential strategic partnering and financing options for its North Carolina project. Given the project’s unique position as the only American spodumene project, with world-class scale, economics, and sustainability, we expect strategic interest to be robust.

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.”