Strongbow Exploration Inc.TSXV:SBW has successfully completed water treatment trials at its South Crofty tin project, located in Cornwall, United Kingdom, and is now working on an application to the U.K. Environment Agency (EA) for a mine waste permit.
The Company has hired WS Atkins, a leading global engineering and project management consultancy, to submit an application to the EA for a mine waste permit with water discharge consent. The application is expected to be filed within one month, and permits are anticipated to be issued before the end of summer this year.
Once the Company receives a mine waste permit with water discharge consent, the South Crofty project will be fully permitted, with the following in place:
- a mining license valid to 2071;
- planning permission to construct new surface process facilities; and
- the ability to dewater the mine.
Richard Williams, CEO and President of Strongbow, commented: “This is an important step forward as Strongbow works to bring the South Crofty mine back into operation. The South Crofty team worked closely with the UK Environment Agency throughout the process and I am very pleased that we were able to develop a system to treat the mine water which met their very high standards. We have resounding local support in Cornwall and I look forward to updating shareholders and the local community during the summer.”
The water treatment trials were required by the EA to demonstrate that contaminated mine water could be treated, and dissolved metals and suspended solids collected prior to discharging mine water from the South Crofty mine workings into the Red River. The results of the trial successfully met all treated water target contaminant levels proposed by the EA.
The water treatment trials were undertaken by a leading UK mine water treatment company, Siltbuster Process Solutions (“Siltbuster”), utilising their High Density Sludge (“HDS”) process and a temporary water treatment plant constructed for the trial period located at the South Crofty mine site. Siltbuster personnel also designed and built the nearby water treatment facility at the Wheal Jane mine, which has been in operation for over fifteen years.
The proposed treatment process for the mine dewatering is a 6-stage system summarised as follows:
- Hydrogen peroxide addition to oxidise As3+ ions to As5+;
- Lime dosing to increase the pH of the mine water from 6.5 to 10.5 and precipitate the soluble metals as hydroxides;
- Addition of polymer to flocculate the precipitated solids;
- Clarification of water and settlement of solids in a lamellar plate thickener;
- Re-circulation of settled solids through the reaction vessel to form a higher density sludge and promote more effective adsorption of soluble metals; and
- CO2 addition to reduce the pH of the treated water below 9 prior to discharge.
Sludge collected in the water treatment process will initially be disposed of at a nearby tailings facility, and once in production will be mixed with tailings as backfill and deposited underground.
The mine waste permit application envisages an initial pumping / treatment rate of 25,000m3 / day over an 18-24 month period. After dewatering the mine is complete and then during production, a steady-state dewatering program of 5,500 to 6,500 m3/day will be maintained, subject to annual precipitation variations. The post-dewatering steady-state treatment rate is based on pumping records from when the mine was in production up to 1998.
The installation and operation of a permanent water treatment plant for the South Crofty tin project will provide a material improvement to the current status of the local environment which currently has untreated, contaminated mine water discharging into the Red River. The cost to construct the permanent water treatment facility is included as part of the estimated USD$118.7 million pre-production capital cost (incl. contingency) outlined in the Company’s PEA announcement dated February 16, 2017 (see below).
About South Crofty
Strongbow acquired the South Crofty tin project from administration in 2016 (see news release dated July 12, 2016 for details). The main points that attracted Strongbow to the project are:
- A mining history that dates back to the 1700s;
- One of the highest grade tin resources globally;
- A mine permit valid until 2071;
- Planning permission to construct new surface facilities;
- Strong local support for the mine to get back into production; and
- Excellent potential to significantly build upon the current NI 43-101 compliant mineral resource base.
The Company published the results of a Preliminary Economic Assessment (“PEA”) on February 16, 2017, and the accompanying NI 43-101 technical report supporting the PEA will be filed on SEDAR before April 2, 2017. The PEA was completed by P&E Mining Consultants Inc. of Ontario, Canada in accordance with guidelines found in National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”).
The PEA indicates that the project is potentially economically viable and technically feasible.
PEA Highlights (All amounts quoted are in USD unless specified otherwise)
- After-tax Net Present Value (“NPV”) of $130.5 million (CDN$170.7 million using an exchange rate of 1.308, at a 5% discount rate) and an Internal Rate of Return (“IRR”) of 23.4%, at assumed metal prices of $10.00/lb Sn, $2.65/lb Cu, and $0.90/lb Zn;
- Estimated pre-production capital cost, including contingency, of $118.7 million with payback of 3.8 years and Life of Mine (“LOM”) sustaining capital costs of $83.8 million;
- Average LOM total cash cost of $3.36/lb SnEq metal recovered and a LOM all-in sustaining cash cost (“AISC”) of $4.44/lb.
- Potential to create approximately 110 new jobs during the 24-36 month dewatering and construction period (excluding construction personnel and contractors);
- A mine at South Crofty would have the potential to directly employ approximately 275 people in permanent positions;
- South Crofty will be operated using modern, trackless, mechanized underground mining methods and best-in-class processing, based on over 40 years of experience processing South Crofty mill feed through both the former on-site and Wheal Jane mills. The thickened tailings from the process will be used to backfill part of an 8-million cubic metres void space currently in the mine as well as providing ground support for modern mining operations;
- The mineralized material mined in the PEA is 2.575 million tonnes containing 88 million pounds of SnEq (tin equivalent) at an average grade of 1.55% SnEq;
- Operating mine life is over an 8-year period using average process recoveries of 88% for tin, 85% for copper, and 70% for zinc.
Disclosure of a scientific or technical nature in this press release was prepared under the supervision of Owen Mihalop, CEng. MIMMM, the Company’s Chief Operating Officer, and Eugene Puritch, P.Eng. and Andrew Bradfield, P.Eng., of P&E Mining Consultants Inc. Messrs. Mihalop, Puritch and Bradfield are “Qualified Persons” as defined in NI 43-101.
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© 2017 Canjex Publishing Ltd.