- Average gold recovery by cyanide leach of 94.8% on Jabali concession samples.
Tarachi CEO Cameron Tymstra commented: “We are very happy with the leaching results from drill samples on the road-accessible Jabali concession. All three samples demonstrated that the mineralized material at Jabali is amenable to gold recovery by cyanide leaching over a range of head grades. With high grades seen in our recent drilling campaigns at Jabali and now positive metallurgical results, we are looking forward to planning our next steps for this project.”
Cyanide Leach Results from Jabali Concession Drill Samples
The objective of this metallurgical test program was to conduct a baseline investigation to determine the samples’ amenability to leaching by cyanidation. The scope of this test program consisted of sample preparation and bottle roll cyanide leaching by the Bureau Veritas Commodities Canada Ltd. BV Minerals Metallurgical Division.
Samples T-1910 and T-1911 were taken from drill hole JAB-21-014 while samples T-0348 and T-0349 were taken from drill hole JAB-20-006 and combined to make up test sample C3. The three leach test samples were chosen to reflect a range of gold grades encountered during the Company’s drilling campaigns around the La Dura mine on the Jabali concession.
The test samples responded very well to leaching by cyanide. Gold extraction from baseline cyanide leaching at 40 wt.% solids in 1.0 g/L NaCN solution for 48 hours varied from 88.4% in sample C3 to 97.8% in sample C2 and averaged 94.8%. Cyanide (as NaCN) consumption averaged 1.73 kg/t. In general, less than 0.5 kg/t hydrated lime was required to maintain a slurry pH above 10.5 during leaching.
Gold leach kinetics as presented in Figure 1 show that gold leached rapidly in the first 24 hours, with an average gold recovery of over 90%. In general, maximum leaching results were attained with a residence time of approximately 30 hours.
Having observed visible free gold in drill hole JAB-21-014 (see press release dated May 12, 2021), testing for recovery by gravity is recommended on a representative sample of drill core and cuttings from the Jabali drill programs. Bond ball mill work index is also recommended on selected samples to determine the samples’ hardness with respect to breakage in ball mills.
Further metallurgical investigation on representative samples is recommended to better optimize process conditions and determine sample variability. Mineralogy analysis with detailed gold mineral search is recommended on leach feed and residues to identify bulk mineralogy, mineral association, and gold carrying minerals as well as gold deportment by gold bearing minerals.
Quality Assurance/Quality Control - Leach Testing Procedures
Three rejects samples were received on the 22nd of July 2021, at BV Minerals Metallurgical Division for this test program. The samples were crushed to >70% 10-Tyler mesh in the BV Minerals Hermosillo (HMS) Lab in Mexico
Each sample was well homogenized and then rotary split out 2 x 2 kg test charges (1kg charge for sample T-1911). One test charge was used for test grind to determine the time required grinding the sample to P80% 75 mm in a laboratory rod mill, and another test charge was used for bottle roll test.
All assays were conducted using industry-standard fire assay procedures.
Grinding and Screening
Wet grinding was performed in a laboratory stainless steel rod mill at a 65% solids pulp density. Particle size distributions were measured using a Rotapävibrator, equipped with 20 cm (8”) diameter test sieves stacked in ascending mesh sizes. The sample was initially wet screened at 37μm (400 Tylerämesh). The +37micron fraction was then dry screened through the stacked sieves. Each fraction was collected and weighed to calculate the individual and cumulative percent retained.
Cyanide Bottle Roll Leach
The bottle roll cyanidation tests were carried out for 48hours on 1-2 kg of P80~75 μm ground samples at 40wt.% solids in leach liquor containing 1.0 g/LNaCN. Before adding sodium cyanide (NaCN), the alkalinity was adjusted with hydrated lime to pH 10.5-11.0 and maintained at this level. During the leach tests, dissolved oxygen was monitored, and intermediate solution samples were removed as required to determine gold dissolution at 2, 7, 24, 30and 48 hours of retention time. Tests were terminated with filtration of leach solution. The solid residues were displacement-washed with cyanide solution, followed by two hot water washes. The leach solution and final residues were analyzed for gold and silver content for metallurgical balances. Reagent concentrations were determined using standard titration methods. The sodium cyanide concentration was determined by titrating with silver nitrate and using para-dimethylamino rhodanine as an indicator.
About Tarachi Gold
Tarachi Gold is a Canadian-listed junior gold exploration company focused on exploring and developing projects in Mexico. The Company’s Tarachi project covers 3,708ha of highly prospective mineral concessions in the Sierra Madre gold belt of Sonora, Mexico in close proximity to Alamos Gold’s Mulatos mine and Agnico Eagle’s La India mine. Tarachi has also acquired the Magistral Mill and tailings project in Durango, Mexico. Magistral includes a 1,000 tpd mill and access to a tailings resource (non-compliant with NI 43-101) estimated to contain 1.3Mt at 2.05g/t Au which the Company expects to bring into production in 2022.
Lorne Warner, P.Geo, VP Exploration and Director of the Company is a qualified person as defined by National Instrument 43-101 and has reviewed and approved the scientific and technical disclosure in this news release.
SPECIAL NOTE REGARDING FORWARD LOOKING STATEMENTS
This news release includes certain “Forward‐Looking Statements” within the meaning of the United States Private Securities Litigation Reform Act of 1995 and “forward‐looking information” under applicable Canadian securities laws. When used in this news release, the words “anticipate”, “believe”, “estimate”, “expect”, “target”, “plan”, “forecast”, “may”, “would”, “could”, “schedule” and similar words or expressions, identify forward‐looking statements or information. These forward‐looking statements or information relate to, among other things: future exploration programs, and the completion of drill holes; and receipt of assay results.
Forward‐looking statements and forward‐looking information relating to any future mineral production, liquidity, enhanced value and capital markets profile of Tarachi, future growth potential for Tarachi and its business, and future exploration plans are based on management’s reasonable assumptions, estimates, expectations, analyses and opinions, which are based on management’s experience and perception of trends, current conditions and expected developments, and other factors that management believes are relevant and reasonable in the circumstances, but which may prove to be incorrect. Assumptions have been made regarding, among other things, the price of silver, gold and other metals; no escalation in the severity of the COVID-19 pandemic; costs of exploration and development; the estimated costs of development of exploration projects; Tarachi’s ability to operate in a safe and effective manner and its ability to obtain financing on reasonable terms.
These statements reflect Tarachi’s respective current views with respect to future events and are necessarily based upon a number of other assumptions and estimates that, while considered reasonable by management, are inherently subject to significant business, economic, competitive, political and social uncertainties and contingencies. Many factors, both known and unknown, could cause actual results, performance or achievements to be materially different from the results, performance or achievements that are or may be expressed or implied by such forward‐looking statements or forward-looking information and Tarachi has made assumptions and estimates based on or related to many of these factors. Such factors include, without limitation: the Company's dependence on one mineral project; precious metals price volatility; risks associated with the conduct of the Company's mining activities in Mexico; regulatory, consent or permitting delays; risks relating to reliance on the Company's management team and outside contractors; risks regarding mineral resources and reserves; the Company's inability to obtain insurance to cover all risks, on a commercially reasonable basis or at all; currency fluctuations; risks regarding the failure to generate sufficient cash flow from operations; risks relating to project financing and equity issuances; risks and unknowns inherent in all mining projects, including the inaccuracy of reserves and resources, metallurgical recoveries and capital and operating costs of such projects; contests over title to properties, particularly title to undeveloped properties; laws and regulations governing the environment, health and safety; the ability of the communities in which the Company operates to manage and cope with the implications of COVID-19; the economic and financial implications of COVID-19 to the Company; operating or technical difficulties in connection with mining or development activities; employee relations, labour unrest or unavailability; the Company's interactions with surrounding communities and artisanal miners; the Company's ability to successfully integrate acquired assets; the speculative nature of exploration and development, including the risks of diminishing quantities or grades of reserves; stock market volatility; conflicts of interest among certain directors and officers; lack of liquidity for shareholders of the Company; litigation risk; and the factors identified under the caption “Risk Factors” in Tarachi's management discussion and analysis. Readers are cautioned against attributing undue certainty to forward‐looking statements or forward-looking information. Although Tarachi has attempted to identify important factors that could cause actual results to differ materially, there may be other factors that cause results not to be anticipated, estimated or intended. Tarachi does not intend, and does not assume any obligation, to update these forward‐looking statements or forward-looking information to reflect changes in assumptions or changes in circumstances or any other events affecting such statements or information, other than as required by applicable law.