Millennial Lithium Corp., Vancouver, Canada, (ML: TSX.V) (A3N2:GR: Frankfurt) (MLNLF: OTCQB) has achieved a significant milestone with the production of lithium carbonate of Battery Grade (BG) purity from the first batch of brine processed through the Company’s pilot plant at its Pastos Grandes Project in Salta Province, Argentina. The pilot plant produced lithium carbonate with a purity of 99.96%. Typical Battery Grade quality lithium carbonate is > 99.5% purity. The brine feedstock was derived from the Company’s Production well PGMW17-04 on the Pastos Grandes Salar which was pumped to ponds that concentrate the lithium carbonate by solar evaporation.
Analytical work on the lithium carbonate samples was completed first at the project development park laboratory, with check analyses performed by Kemetco Research Inc. of Richmond, B.C.., Canada In addition to check chemical analyses Kemetco also conducted physical testing, including Particle Size Determination (PSD) and a scanning electron microscope (SEM) study for crystal habit determination. The PSD test results indicate the lithium carbonate product has a typical size distribution and is amenable to micronization to meet battery application requirements.
Farhad Abasov, President and CEO, commented “The Company is very pleased to have reached this significant milestone with our pilot plant producing from the very first run Battery Grade quality lithium carbonate. The analytical results from this first batch indicate Battery Grade lithium carbonate can be produced prior to the CO2 purification stage, and with CO2 purification, we have the potential to produce a superior premium BG lithium carbonate product which may command a price premium. This has been accomplished using a proven flowsheet as outlined in the original plant design in the Company’s Feasibility Study (see press release July 29, 2019). We have also demonstrated that we have the option to produce high quality Technical Grade and Battery-Grade product at lower cost than estimated in the Company’s Feasibility Study using the basic processing.”
The process design for Millennial’s Pastos Grandes Project incorporates industry standards to produce lithium carbonate which is typically Technical Grade, and then a further lithium bicarbonate purification stage in order to consistently produce very high quality lithium carbonate.
In Millennial’s pilot plant, a first stage lithium carbonate (Technical Grade – basic Battery Grade) is produced, which can be further purified by re-crystallization using the addition of CO2 in order to make a lithium bicarbonate solution. This solution is filtered to remove final impurities, heated, the CO2 recovered and lithium carbonate re-crystalized as a consistent battery-quality lithium carbonate. This first brine batch yielded two lithium carbonate samples; the analytical results of both products are shown in Table 1. As outlined in the results the Millennial team was successful in producing Battery Grade quality lithium carbonate at the completion of the basic stage and a premium quality Battery Grade at the completion of the purification process.
The impurity levels in the lithium carbonate product are very low and meet the specifications for Battery Grade qualifications from battery manufacturers (see Table 1). Typical impurities in lithium carbonate for battery production include Na, Ca, SO4, K, and B. All these elements showed low values in the lithium carbonate produced in the Pastos Grandes project pilot plant. Table 1 below shows results as reported by Kemetco, a private sector integrated science, technology and innovation company, and confirmed Millennial´s internal laboratory results, with the addition of Loss On Ignition (LOI) at 500 degrees Celsius for 30 minutes, and contents for additional minor impurities. Kemetco provides laboratory analysis and testing, field work, bench scale studies, pilot plant investigations, consulting services, applied research and development for both industry and government. Kemetco has experience with a wide variety of metals such as lithium, nickel, cobalt, manganese, copper, zinc, lead, gold, silver, vanadium and platinum group metals. Kemetco’s clients range from start-up companies developing new technologies to large multinational corporations with proven processes.
Table 1 Analytical results of lithium carbonate samples (dry basis). *Other impurities include Cl, Si, Al, Ba, Co, Cr, Fe, Mn, Ni, P, Zn.
The analytes concentration of Boron, Calcium, Magnesium, Potassium, Sodium, and Sulphate were quantified by ICP-OES (Inductively Coupled Plasma – Optical Emission Spectrometry) with an appropriate calibration method using high purity standards. Chloride concentration was determined by the mercuric thiocyanate colorimetric method. LOI at 500 degrees Celsius for 30 minutes was quantified by the gravimetric method. The Lithium Carbonate assay was then calculated by subtraction of impurities. A minor amount of insoluble material which has not been included was introduced by the first use of the equipment and by additional handling, both of which have been resolved for subsequent trials.
In addition to the standard purity and impurity analyses, the Company also engaged Kemetco to determine the product Particle Size Distribution (PSD) via laser diffraction and analysis by Scanning Electron Microscope (SEM) to assist in determining crystal habit and morphologies. The main PSD metric for battery quality product is the D50 value which identifies the maximum particle size for 50% of the product. The D50 for the Premium Battery Grade product is 67µm (ie 50% of the product is less than 67µm, or 0.067mm) and for the Battery Grade product is 177µm, similar to values from other pre-micronized lithium carbonate products of existing producers. The Company is currently planning and preparing additional samples to be sent for comprehensive micronization studies targeting final product with a D50 of 5µm (5 microns which is the optimal value for a battery grade product. The SEM work has confirmed the particle size and the morphology of the lithium carbonate crystals for the Premium Battery Grade sample is predominantly tabular, while the primary stage Battery Grade sample is characterized by rosette aggregates of similar blades. Both appear to be amenable to micronization.
The Company initiated pilot pond construction in 2018 and began directing brine to the ponds later that same year. The pilot plant is being fed with concentrated lithium-rich brine from smaller feeder ponds which had reached a target grade of 3% Li. Brine chemistry, particularly K, B, Ca, Mg, and SO4 concentrations are in line with target specifications and plant design parameters outlined in the Company’s Feasibility Study completed in 2019 (see press release July 29, 2019). The first phase of the process, the Solvent Extraction (SX) system was successful in removing the majority of the boron (B) from the brine. The SX stage is followed by brine purification via carbonation and liming reactors designed to remove calcium (Ca) and magnesium (Mg). After this initial carbonation stage the concentrated brine is directed through to the first ion exchange (IX) columns to further reduce remaining trace Ca, Mg and B, followed by the main lithium carbonate precipitation reactor which in this trial yielded a Battery Grade product. Lastly, the CO2 purification stage which includes a second IX ensures consistent premium Battery Grade purity.
As part of the pilot plant operation and training the Company’s engineering department identified optimization opportunities in reactor construction and brine heating, and introduced more efficient and faster solid liquid separation techniques in order to achieve a purified brine. These changes are currently being implemented and upon completion a second batch of brine will be processed as the pilot plant continues to ramp up production.