Precious Metals - Gold, Silver and Platinum
ACA Howe International have been involved in gold, silver and platinum projects in 68 countries in Africa, Asia, Australasia, Europe, North America and South America, encompassing exploration, resource estimation, mining and processing for hard rock and alluvial precious metal projects. We have written over 500 formal reports for gold, silver and platinum projects including project evaluation, due diligence studies and technical reporting for stock exchange listings. Among many successful projects, ACA Howe were involved in the discovery of Semafo’s Mana Gold Mine in Burkina Faso.
Our experience is complimented by the considerable experience of our Associates who offer a wealth of expertise to our clients, with achievements including the discovery of precious metal deposits, and the planning and optimising of existing mining operations.
Selected Gold, Silver and Platinum Projects
- Resource estimation study of two silver projects in Argentina.
- Competent Persons’ Report on platinum and gold mining prospects in South Africa.
- Technical report on gold exploration properties in the Philippines.
- Review of geology, reserves, plant and metallurgical testwork for a silver mining project in Morocco.
- Geotechnical review of platinum mining and exploration projects in Russia.
- A review of gold deposits throughout West Africa.
- Project appraisal to determine the exploration potential of a silver deposit in Mexico and make recommendations for future work.
- Geological mapping, structural analysis and resolution of mineralisation controls at a gold mine in western Ghana.
- Satellite image interpretation including lithostructural and alteration mapping for a gold exploration project in Argentina.
- Technical review of platinum and gold exploration projects in Ethiopia and Sierra Leone.
- NI 43-101 compliant technical reporting for a gold exploration project in Kazakhstan.
Case Study - Gold Mining, Metallurgy and Exploration
In 2012, ACA Howe International were commissioned by a UK based lender to conduct due diligence on an existing investment in a narrow vein, underground gold mine in Central America. After an initial site visit and due diligence report, ownership of the property was transferred to the lender and ACA Howe led exploration, mining and processing studies through to 2015. The work involved geologists, mining engineers and metallurgists and achievements included the identification of high grades gold zones and bringing the safety standards in line with international standards.
Due Diligence
A site visit was completed by ACA Howe's Senior Geologist, Mining Engineer and Metallurgist in order to appraise the project and make recommendations on areas for improvement.
Specific tasks completed include the following:
- Underground and surface channel sampling was completed on the two major veins in order to determine the validity of the historical results, including gold and silver assay grades and vein widths.
- Assessment of mine condition and recommendations on mining methods.
- Evaluation of processing plant condition and recommendations for equipment upgrades.
- Initial cost modelling in order to determine the project potential.
Exploration and Mine Rehabilitation
Exploration included the channel sampling of extensions of the main veins and new veins identified by ACA Howe geologists. A geological model was developed and tested by drilling in order to guide future mining operations.
Rehabilitation of existing workings was led by ACA Howe mining engineers in order to bring the working conditions in line with modern standards. Issues encountered were occasional earthquakes and soft ground in parts.
Underground Development
ACA Howe geologists and mining engineers led the underground development phase, including face mapping and sampling, guidance on mining equipment, mining methods, safety and underground surveying.
Case Study - Gold Exploration
In 2012, ACA Howe were commissioned by a Nigerian company to make recommendations for the exploration of two licences in Sierra Leone and to supervise the subsequent exploration programmes. ACA Howe utilised licence scale exploration techniques and have delineated target areas for detailed geological mapping and surface sampling.
Compilation of Regional Data and Satellite Image Interpretation
Regional geological maps and geochemical data were compiled into a database by ACA Howe to give an initial indication of potential targets. This was combined with satellite image interpretation of Landsat, Aster and High Resolution imagery to produce a lithostructural map, identify alteration zones and define target areas. The study resulted in the delineation of 10 target areas for follow-up exploration, based on interpreted greenstone lithologies and circular features.
Geophysical Interpretation
Interpretation of existing airborne geophysical data was undertaken by ACA Howe in order to refine targets from satellite image interpretation and to determine whether any further targets for exploration could be identified. Overall the study showed close lithological correspondence to the satellite image interpretation. A high intensity feature, likely to be a banded iron formation within greenstone belt, provided further evidence for and extended the major target area for follow-up exploration. The presence of a circular feature was also confirmed, which could represent an unexposed intrusion and potential source of hydrothermal fluids.
Follow-Up Reconnaissance Exploration
A site visit was completed by a Senior ACA Howe Geologist in order to ground truth interpreted lithology, structure and alteration from satellite image and geophysical interpretations. In addition, a licence-wide stream sediment survey was conducted by ACA Howe in conjunction with local geologists. Results of the survey provide confirmation of the most prospective area for detailed exploration.
© 2017 A.C.A. Howe International Limited
