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Ethiopia
Da Tambuk Project

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 Location:
33km NW from Indaselassie, Ethiopia

  Project Contacts:
700 - 1055 W.Georgia Street
Vancouver
British Columbia, Canada
PO Box 11108
Phone  ...  Subscription required
Fax+1-604-899-1240
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  • Mining
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  • Filings & News

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Overview

StagePermitting
Mine TypeUnderground
Commodities
  • Gold
  • Silver
  • Copper
Mining Method
  • Cut & Fill
  • Sub-level stoping
Processing
  • Gravity separation
  • Agitated tank (VAT) leaching
  • Carbon in leach (CIL)
  • Elution
  • Solvent Extraction & Electrowinning
  • Cyanide (reagent)
Mine Life4 years (as of Jan 1, 2018)
Latest NewsEast Africa Metals Completes Adyabo Transaction, Receives Schedule for Adyabo Mine Development     January 24, 2020


Owners

Source: p. 17
CompanyInterestOwnership
East Africa Metals Inc. 100 % Indirect
East Africa Metals Inc. (EAM) through its wholly-owned subsidiary Tigray Resources Inc. (TRI) owns the Adyabo Project, which includes the Mato Bula and Da Tambuk deposits.

Deposit Type

  • VMS
  • Orogenic


Summary:

The geology near the Da Tambuk deposit comprises a northeast trending assemblage, from west to east, that includes a thick sequence of black and grey shales (locally with rare graphitic beds), mafic tuff and bedded chert, chlorite sericite schist and variable chlorite sericite schist. Locally, the assemblage is intruded by feldspar phyric quartz eye porphyry, and leuco grabbroic units. In the area of mineralization, strong silicification is noted locally, along with quartz veining.

A zone of phyllic alteration (sil-ser-py) has been mapped over 700 m of north-south trending strike between the Mato Bula north and Da Tambuk south. This zone of alteration may prove to be the linking structure between the Mato Bula north and Da Tambuk prospect, and if true, presents 700 m of prospective strike.

This trend passes 200 m to the east of Mato Bula North, which is a gold-rich volcanichosted massive sulphide (VHMS)-type target found on the southern licence boundary of the Adi Dairo concession. The alteration indicates that Da Tambuk prospect appears to be on a separate trend with Mato Bula and Silica Hill. This hypothesis is supported by the different geochemical nature of Mato Bula North (high copper, low gold) verses Mato Bula, Silica Hill and Da Tambuk (high gold, low copper). In addition, Mato Bula and Silica Hill are hosted within altered schist, whereas Mato Bula North is hosted higher up in the sequence in the VTSM unit. However, this theory cannot be confirmed without further detail mapping to the south.

Foliation in the area is trending south- southwest (190°), dipping steeply (60 to 80°) towards west-northwest, locally swinging up to 30° to trend 218°, dipping (80 to 85°) towards northwest.

Exploration efforts on the Adyabo Property currently target two deposit types: gold-rich VHMS and orogenic lode-gold mineralization. A spatial relationship between these deposit types is noted on the property and may be related to reactivation of hydrothermal pathways or redistribution of deposited mineralization during orogenesis.

The Da Tambuk deposit, located 4 km northeast along strike from Mato Bula, was originally targeted due to its intense alteration signature determined from Landsat image interpretation. Systematic exploration, including reconnaissance regional soil sampling, delineated a 1.2 km long gold-in-soil anomaly with concentrations greater than 100 ppb gold. Local associations of lead and molybdenum soil anomalies were also present. The highest gold concentration recorded in soils was 5 ppm gold, and no previous artisanal workings were identified in this area. Several trenches were excavated, and one trench intersected 16 m grading at 3.95 g/t gold, including 4 m at 14.53 g/t gold.

Upon initiation of trenching, artisanal activities commenced. Staged trenching and subsequent drilling determined that mineralization is associated with moderate to intense silica alteration and quartz veining, and disseminated to semi-massive pyrite, minor chalcopyrite, and sphalerite. The host rock is a pyrite-rich (greater than 10%) sericite schist that attains a thickness of 50 m.


Mining Methods

  • Cut & Fill
  • Sub-level stoping


Summary:

A combination of cut-and-fill mining and sublevel stoping was considered for the underground operations. Cut-and-fill will be used to mine areas with irregular mining shapes that would be unsuitable for sublevel stoping, which is a bulk mining method.

Cut-and-fill requires placing waste rock or tailings into mined out excavations for use of both as ground support and as a working platform for subsequent mining cuts.

Sublevel stoping does not necessarily require backfill. The method involves blasting large voids underground that become non-entry stopes. The method requires using remote control mucking equipment, which is standard practice in modern underground mining.

CUT-AND-FILL MINING
The proposed cut-and-fill mining involves the following steps:

1. An attack ramp is driven off the main access ramp at a grade of -15% into the mineralization.

2. The first cut is excavated by driving along the vein to the width of the vein. This may be done in stages to allow partial backfilling of mined-out areas.

3. If the mineralization is narrow, blast holes will be drilled upwards into the next cut and “slashing” the rock down into the first cut. If the mineralization is wide or if rock stability is not adequate for large spans, then the first cut will be backfilled immediately after mining. For both options, this step involves backfilling the mined-out void with rock, tailings, cemented rock, or cemented tailings.

4. The attack ramp is slashed to raise the access to the next cut elevation.

5. Steps 1 to 4 are repeated until the stope height is mined out. Depending on the situation, a sill or crown pillar is left between stopes as regional support and to support the backfill.

SUBLEVEL STOPING
Sublevel stoping generally involves establishing a system of stope access tunnels for drilling blastholes and for loading blasted ore. Blasthole drilling drifts are driven into the mineralization to allow access for longhole drilling equipment. Drawpoints are then developed at a lower level to enable mucking of blasted ore.

Sublevel stoping is undertaken in overhand and underhand configurations. Overhand configurations involve advancing lower panels of a stope to be mined out first, after which the upper panels are mined out, dropping the rock to drawpoints located at the lowest point of the stope.

With underhand configurations, the stope is mined out from the top to the bottom, with blasted rock being mucked from each level. Blastholes are drilled upwards from the sill drives, with rock mucked from the same drive used for drilling.

In the case of Da Tambuk, underhand sublevel stoping is considered appropriate, since this approach minimizes the length of time between developing stopes and production from stopes.

The underground operations will be accessed through a 3 m by 3 m spiral access ramp. The main ramp will commence at an elevation of 1,239.5 m and descend to an elevation of 1,091 mamsl. Stopes will be accessed through 30 m long crosscuts into the mineralization.

The mine has been designed with the following criteria:

• minimum (cut-off) gold grade included in mine plan of 2.2 g/t

• crown pillar of 10 m left against surface

• minimum mining width of 2 m

• main ramp tunnel dimensions 3 m high by 3 m wide

• cross cut tunnel dimensions 2.5 m high by 2.5 m wide

• maximum grade of ramps 15%

• maximum grade of crosscuts –15% (for attack ramps)

• vertical spacing of levels of 15 m

• ventilation shaft diameter of 3 m

• maximum height of cut-and-fill lift of 5 m

• maximum height of sublevel stoping panel of 15 m.


Crushing and Grinding


Processing

  • Gravity separation
  • Agitated tank (VAT) leaching
  • Carbon in leach (CIL)
  • Elution
  • Solvent Extraction & Electrowinning
  • Cyanide (reagent)

Flow Sheet: Subscription required

Summary:

The Da Tambuk processing facilities are designed to process at a nominal rate of approximately 200,000 t/a, or 550 t/d, of gold- silver bearing material from an underground mining operation to produce gold-silver doré product.

The proposed process flowsheet is summarised as follows:

- Conventional crushing and ball mill grinding for comminution with a cyclone for particle size classification of the ground mill feed. A centrifugal gravity concentrator in the grinding circuit will be used to recover coarse and liberated gold particles, and a shaking table will be used to up-grade the gravity concentrate before smelting.

- The ball mill cyclone overflow will be treated in a six-stage CIL circuit to extract gold and silver from the feed material using sodium cyanide solution. The extracted gold and silver will be adsorbed from this solution onto activated carbon.

- The gold and silver loaded carbon will initially be acid-washed to remove c ........

Recoveries & Grades:

CommodityParameterAvg. LOM
Gold Recovery Rate, %  ......  Subscription required
Gold Head Grade, g/t 4.88
Silver Recovery Rate, %  ......  Subscription required
Silver Head Grade, g/t 2.27
Subscription required - Subscription is required.

Projected Production:

CommodityUnitsLOM
Gold koz 95
Silver koz  ......  Subscription required
All production numbers are expressed as metal in doré.

Operational Metrics:

Metrics
Daily ore mining rate  ......  Subscription required
Waste tonnes, LOM  ......  Subscription required
Ore tonnes mined, LOM  ......  Subscription required
Daily processing capacity  ......  Subscription required
Tonnes processed, LOM  ......  Subscription required
Annual processing capacity  ......  Subscription required
* According to 2018 study.
Subscription required - Subscription is required.

Reserves at May 30, 2018:

CategoryTonnage CommodityGradeContained Metal
Indicated 775,000 t Gold 4.51 g/t 112,000 oz
Indicated 775,000 t Silver 2.4 g/t 59,000 oz
Indicated 775,000 t Copper 0.11 % 1.9 M lbs
Indicated 775,000 t Gold Equivalent 4.65 g/t 116,000 oz
Inferred 110,000 t Gold 4.04 g/t 14,000 oz
Inferred 110,000 t Silver 2.93 g/t 10,000 oz
Inferred 110,000 t Copper 0.06 % 0.2 M lbs
Inferred 110,000 t Gold Equivalent 4.13 g/t 15,000 oz

Commodity Production Costs:

CommodityUnitsAverage
Cash costs Gold USD  ......  Subscription required *
Cash costs Gold USD  ......  Subscription required *†
All-in sustaining costs (AISC) Gold USD  ......  Subscription required *†
Assumed price Silver USD  ......  Subscription required *
Assumed price Gold USD  ......  Subscription required *
* According to 2018 study / presentation.
† Net of By-Product.
Subscription required - Subscription is required.

Operating Costs:

Units2018
UG mining costs ($/t milled) USD 31 *
Processing costs ($/t milled) USD  ......  Subscription required
Total operating costs ($/t milled) USD  ......  Subscription required
* According to 2018 study.
Subscription required - Subscription is required.

2018 Study Costs and Valuation Metrics :

MetricsUnitsLOM Total
Initial CapEx $M USD  ......  Subscription required
Sustaining CapEx $M USD  ......  Subscription required
Total CapEx $M USD  ......  Subscription required
UG OpEx $M USD  ......  Subscription required
Processing OpEx $M USD 14.2
G&A costs $M USD 5.9
Total OpEx $M USD  ......  Subscription required
Income Taxes $M USD  ......  Subscription required
Net revenue (LOM) $M USD  ......  Subscription required
Net Operating Income (LOM) $M USD  ......  Subscription required
After-tax Cash Flow (LOM) $M USD  ......  Subscription required
Pre-tax NPV @ 8% $M USD  ......  Subscription required
After-tax NPV @ 8% $M USD  ......  Subscription required
Pre-tax IRR, %  ......  Subscription required
After-tax IRR, %  ......  Subscription required
After-tax payback period, years  ......  Subscription required
Subscription required - Subscription is required.

Proposed Heavy Mobile Equipment as of April 30, 2018:
HME TypeSizeQuantity
Drill jumbo (two boom) 2
....................... Subscription required ....................... Subscription required 2
....................... Subscription required ....................... Subscription required 1
....................... Subscription required ....................... Subscription required 1
....................... Subscription required ....................... Subscription required 1
....................... Subscription required ....................... Subscription required 3
Subscription required - Subscription is required.

Subscription required - Subscription is required.

Staff:

EmployeesTotal WorkforceYear
Subscription required Subscription required 2018

Corporate Filings & Presentations:

DocumentYear
................................... Subscription required 2018
Subscription required - Subscription is required.

News:

NewsDate
East Africa Metals Completes Adyabo Transaction, Receives Schedule for Adyabo Mine Development January 24, 2020
East Africa Metals Closes Tibet Huayu Development Financing August 23, 2019
East Africa Metals Awarded Mining Licenses for Mato Bula and Da Tambuk Projects, Ethiopia – Revised and Amended May 29, 2019
East Africa Metals Advances Mato Bula and Da Tambuk Mine Permitting Process May 28, 2018

Aerial view:

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