La Demajagua Gold/Silver Mine

DEVELOPMENT CONCEPT AND RESOURCES

The proposed La Demajagua mine on the Isle of Youth in south west Cuba is in the predevelopment stage with the current Definitive Feasibility Study (“DFS”) for the first stage open pit mine expected to be completed in time for a final development decision in Q4 2022.

SITE LOCATION AND INFRASTRUCTURE

  • The La Demajagua gold/silver deposit is located on the Isle of Youth, 100km from mainland Cuba.
  • The mine site is accessible from the port city of Nueva Gerona by 40km paved highway.
  • A dedicated port can be constructed for landing craft, 4km from mine.
  • Connected to water, electricity, and fibre optic.
  • 900ha mining concession at 20m above sea level.

Location La Demajagua Gold/Silver Project

LOWER
Tonnes 16,000,000
Grade (Au g/t) 2.3
oz Au 1,200,000
Grade (Ag g/t) 17
oz Ag 8,700,000
UPPER
Tonnes 20,000,000
Grade (Au g/t) 2.7
oz Au 1,700,000
Grade (Ag g/t) 25
oz Ag 14,800,000

Based on extensive historic drilling and metallurgical test work, the open pit mine is planned to operate for six years at a mining rate of 800,000 tpa of ore with a stripping ratio of 7:1, to produce 60,000 tpa of concentrate containing approximately 100,000 oz Au equivalent.

Data from 50,000m of drilling by Canadian mining companies together with a 15,000m program completed by MLV in August 2021, and a current 10,000m program will allow the establishment of JORC Resources for the project in early 2022.

Additional drilling will be required for the second stage underground operations which are expected to be at around 70% of the production rate for the open pit, for a minimum of at least 10 years.

As announced to ASX on 10 November 2020, the Exploration Target Range estimated by Cube Consulting for the La Demajagua deposit at a 1.0 g/t Au cut off is between 16,000,000 tonnes at 2.3 g/t Au and 17 g/t Ag, and 20,000,000 tonnes at 2.7 g/t Au and 25 g/t Ag.

Geological modelling to date has indicated the head grades for the open pit could be higher than in the Exploration Target Range.

The composite sample from drill cores currently being tested by SGS to establish gold/silver recoveries and concentrate grades contains 3.9 g/t Au and 37.0 g/t Ag with final grades to be determined when JORC Resources are established.

Drilling at La Demajagua

Initial High Grade Intercepts advised to ASX on 22 June 2021

HISTORY

The La Demajagua gold/silver deposit incorporates the Delita deposit which was discovered around 1900 but received only cursory attention until the 1920s when a North American company acquired the concession. Production was minimal until after World War ll.

In the period 1947 – 1950, approximately 60,000 t of ore were mined underground. As mining progressed in depth, the material changed from shallow, oxide-zone material, to sulphidic arsenic mineralization. Reports suggest that 60,000 t were mined at a recovered grade of 14 g/t gold. A 40 tpd beneficiation plant was constructed to drive off arsenic and sulphur, and concentrates were shipped offshore to a smelter for direct refining. The property was abandoned in 1958 when the concentrator ceased operating.

During the 1970s and 1980s, regional exploration, mapping and geophysical surveys were conducted, and between 1977 and 1980, trenching and drilling were conducted on the Delita property. This work expanded resources considerably.

Following a 1980 study, a new shaft was sunk and a flotation and gravity process plant constructed, with approximately 80,000 t of ore processed through the plant. High recoveries of gold and silver, reporting to flotation and gravity concentrates, were achieved in the plant, which had a nominal 60-80 tpd capacity. However, the inability to process the refractory concentrates prevented operations from being expanded to full scale production.

Concentrate product was reported as 30g/t to 60g/t Au, 15% to 20% As and 20% to 30% S.

 

Previous Preliminary Feasibility Studies

Boliden Contech, working under a technical assistance program for Cuba, prepared a Prefeasibility Study of the Delita deposit in June 1990. It was concluded that the project was not viable at gold prices prevailing at that time, primarily because the metallurgical treatment was likely to be expensive and a costly undercut-and-fill method was proposed for underground mining.

In May 1992, Minproc Engineers prepared a Prefeasibility Study of Delita for Matlock Mining NL of Australia. Minproc evaluated metallurgical test work and concluded that the project was economically viable.

Minera Mantua SA acquired its interest in the Delita project in 1993 and engaged Davy Engineering to conduct a Preliminary Feasibility Study for the project, which was completed in March 1995 and reported average head grades that reflect the anticipated grades assessed by the Company’s consultants after geological modelling of historic drill data.

In September 1994, after metallurgical test work on the Delita ore, Davy Engineering reported concentrate grades of 46.8g/t Au, 380g/t Ag, 18%As, and 16%S.

FINANCIAL

The current Financial Model for the open pit mine indicates a total capital cost of US$73 million including pre-development costs, financing and MLV’s administration costs during construction.

Antilles Gold is contributing US$13.0 million of this amount between October 2020 and March 2023 for its 49% shareholding in MLV.

Modelling is based on quotations for the mining fleet and turnkey offers for the design and construction of the crushing, milling, and flotation circuits, and an 8Mw power station.

Antilles Gold’s equity will meet the costs of the DFS and MLV’s overheads to December 2022 (US$7.0 million), and mine infrastructure in 2023 (US$6.0 million).

Financing for US$60 million of development costs is anticipated to be provided by a combination of supplier credit and project loans.

Concentrate is expected to be sold to one or two plants in eastern Russia that import and process concentrate with high arsenic content, as will be produced at La Demajagua.

Results from MLV’s financial modelling indicate very acceptable returns which cannot be advised to the ASX prior to establishment of JORC Indicated Resources in early 2022.

Florencia & Maclama Open Pit Mines

The Florencia and Maclama gold deposits near Guaimaro, 100km south east of the Provincial capital of Camaguey, are low sulphide, near surface deposits which have been explored by Russian companies, and MacDonald Mines from Canada

Geological data from 17,000m of cored drill holes (237 holes), and an 80m shaft at Florencia with 1200m of drifts and cross cuts, has been made available to Antilles Gold.

Metallurgical test work on Florencia ore by SGS Lakefield in Canada indicated concentrate grades could be up to 120 g/t Au and 90 g/t Ag with a very low arsenic content (0.05% As).

The deposits are approximately 7km apart and the plan is to develop two pits with ore being transported to a central plant for the production of concentrate.

It is anticipated that if the development proceeds, the capital costs for the two relatively small mines will be able to be met from surplus cash flow generated by the La Demajagua mine.

Annual concentrate production of only 15,000 tonne from each mine at a conservative grade of 50g/t Au would result in the production of approximately 50,000 oz Au per year plus silver credits.

These properties, which are the subject of an Exploration Agreement with GeoMinera, will be further explored by Antilles Gold in 2022-23 and a Prefeasibility Study undertaken prior to the transfer of the two Mining Concessions to MLV for potential project development in 2025.

Golden Hills Open Pit Mine

The Golden Hills sulphide deposit was explored by MacDonald Mines between 1994 and 1998 when they conducted ground and airborne geophysical surveys, mapping, geochemical surveys, trenching, and 199 cored drill holes to an average depth of 80m (50 m into the shallow sulphide mineralization). The database generated by this work was well archived and available for Antilles Gold.

A cluster of three oxide deposits at Golden Hills that have already been mined are underlaid by a large interconnected volcanogenic massive sulphide (“VMS”) deposit which is located 15km from the Florencia and Maclama deposits.

The mineralisation discovered to date lies in a 1.5km long by 1.0km wide west-northwest oriented zone, and within a lens shaped body 7.0km long and 2.0km in true thickness that has been interpreted to be a section through a volcanic edifice.

The extensive geological data for the property provided by GeoMinera will assist in preparing an efficient and cost-effective program to complete the initial exploration and a Prefeasibility Study for the project in 2022-24.

Antilles Gold is attracted to the Golden Hills deposit as it could be a viable producer of large volumes of copper/gold concentrate.

Golden Hills Consulting Geologists Report

Geology

“The Golden Hills Au-Cu deposits are hosted in Cretaceous volcaniclastic rocks, that dip moderately west-northwest. These rocks outline a lens shaped body 7.0km long and about 2.0km in true thickness that is interpreted to be a section through a volcanic edifice.

The mineralization is spatially and probably genetically related to a 2.0km² intrusive body that is centered 1.5km south of Big Golden Hill. The mineralization lies within a 1.0km wide by 1.5 km long west-northwest oriented zone on the northwest side of the intrusive.

The Golden Hills Au-Cu deposits have been classified as high-sulphidication type deposits. The style and distribution of the mineralization and alteration has many similarities to high-sulphidication gold systems around the world including Pueblo Viejo in the Dominican Republic, El Indio in Chile, and Lepanto in the Philippines.

The Golden Hills Au oxide deposits are underlaid by a large mineralized system hosting Au and Cu enriched sulphide bodies. Wide intersections of blind, massive, semi-massive, and disseminated sulphide mineralization with Au and Cu occur within the area, and the potential to define large Au and Cu sulphide resources is excellent.”

Major Target

The Golden Hills deposit represents a major target for Antilles Gold which is planning an aggressive exploration program of the property in 2022-24. The Company will establish a regional office in Camaguey in south east Cuba to conduct the program under the control of Antilles Gold’s Exploration Manager. Exploration costs will be reimbursed to Antilles Gold if the deposit is developed.

Copper/ Gold Deposits

The exploration office will also review the potential of approximately 20 copper/gold deposits provided by GeoMinera prior to Antilles Gold nominating which properties should be retained for exploration, and possible future development.

Interpreted Longitudinal Section through Little Golden Hill

Mined oxide deposits at Golden Hills underlaid by an outcropping interconnected sulphide deposit

La Demajagua Underground Mine

Antilles Gold will undertake a DFS in 2027 for the planned underground operation to follow the open pit mining.

The Company will provide US$6.0 million to undertake the DFS including the drilling necessary for mine planning and resource calculation.

The underground mining rate is expected to be approximately 550,000 tpa with head grades of around 4.0 g/t Au to 4.5 g/t Au and a mine life of at least 10 years.

Expected annual concentrate production of 40,000 tpa should contain approximately 70,000 oz Au equivalent.

Antilles Gold will contribute a further US$7.0 million in 2029 for underground development to maintain its 49% shareholding in MLV, with mining planned to commence in 2030.

The underground operation will benefit from the availability of existing processing plant and infrastructure, and require relatively low additional capital costs for the mine development which should be able to be met from retained earnings of MLV.

Concentrate Processing Facility

Antilles Gold intends to review the technical and commercial viability of constructing a plant at a suitable location in Latin America, to process refractory concentrate sourced from MLV’s mines, and from other regional mines, to produce significantly higher value doré.

 

The oxidation process that would be utilised in conjunction with standard cyanide-in -leach (“CIL”) technology could be either pressure oxidization (“POX”), or Glencore’s patented Albion process (refer TECHNOLOGY section) with which the Company has had considerable experience.

 

The Company’s 200tpd VSPA oxygen plant which is currently stored in the Dominican Republic and is being well maintained, would, if utilised in a new plant, be the major determinant in the capacity of the concentrate processing facility.

This oxygen plant would satisfy the demands of either a mini 60,000 tpa POX plant, which equates to the proposed annual concentrate production from La Demajagua, or an Albion oxidation circuit with the capacity for two trains of 60,000 tpa each.

Las Lagunas Oxygen Plant

ANTILLES GOLD LIMITED
ASX CODE AAU
OTCQB:ANTMF
55 Kirkham Road
Bowral NSW 2576
Australia
+ 61 2 4861 1740
ANTILLES GOLD LIMITED
ASX CODE AAU
55 Kirkham Road
Bowral NSW 2576
Australia
+ 61 2 4861 1740