Overview
Stage | Production |
Mine Type | Underground |
Commodities |
|
Mining Method |
|
Processing |
- Gravity separation
- Flotation
- Carbon in leach (CIL)
- Carbon in pulp (CIP)
- Carbon adsorption
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 2021 |
Al Amar mine produces a high grade gold rich polymetallic ore, which is processed into gold in dore and in copper and zinc sulphide concentrates, which are sold to overseas smelters. The owner did not report Cu and Zn production numbers. |
Deposit Type
- Breccia pipe / Stockwork
- Vein / narrow vein
Summary:
Rocks of the Al Amar region are part of the Ar Rayn Terrane, a regional tectono-stratigraphic unit. This unit is separated from the western Abt Schist Belt by the regional Al Amar-Idas fault. Rocks of the Ar Rayn Terrane are overlain by Paleozoic sedimentary rocks to the northeast and south.
The deposit is located in a north-south trending belt of felsic to mafic volcanic rocks comprising the Al Amar Group. Rocks of the Al Amar Group are transitional in composition from tholeiitic to calc- alkaline. The rocks are comprised of volcanics, submarine exhalatives, carbonates and cherts. The Al Amar Group rocks are intruded by granodiorite, trondhjemite, gabbro and quartz diorite rocks coeval or following tectonism of the group dated at 700Ma to 600Ma. Post tectonic granites dating 580Ma also intrude the Al Amar rocks. The metamorphic grade of rocks in this region ranges from lower greenschist facies to the west and amphibolite facies to the east.
Structurally the Al Amar Group rocks have been subjected to complex folding and faulting. Predominant structures trend north-south and northeast-southwest. Structures at the Al Amar deposit are dominated by northwest-southeast and west northwest-east southeast fault systems and are associated with mineralisation.
Three spatially discrete zones of mineralisation have been identified at Al Amar. The main mineralised zone is the North Vein Zone (the “NVZ”). This zone strikes east-west with a dip of 69° to 80° to the south. The NVZ has been identified extending 550m along strike and to a depth of 350m. The zone is reported to be 10m to 45m wide. Mineralisation in this zone has been interpreted to occupy a tension fracture system developed late during deformation processes. It is hosted by progressively higher stratigraphic units from east to west. Two sub-parallel vein systems have been identified within the zone. The vein systems occur as a series of sub-vertical, discontinuous quartz veins up to 0.5m thick associated with sub- massive sphalerite, pyrite and minor chalcopyrite mineralisation. The Footwall Vein (“FWV”) is characterized by high copper values, high zinc and sporadic high gold values. Contrastingly the Hanging Wall Vein (“HWV”) is associated with moderate copper, zinc and gold values and elevated lead levels. Mineralisation is open laterally and at depth. A northeast-southwest trending fault cuts off mineralisation to the west.
The Stockwork Zone (“SZ”) and South Vein Zones (“SVZ”) are comprised of irregular stockwork and discontinuous vein systems respectively. Both zones are hosted in Unit 3. Mineralisation in the SZ is similar to mineralisation in the NVZ. The SVZ is associated with talc carbonate beds. The SVZ occurs in a wide fault zone 20m to 30m wide. This zone is structurally complex and shows little continuity along strike or down dip.
Rocks of the Al Amar deposit comprise a volcanic sequence starting at the footwall of the main zone of mineralisation. The units are outlined below:
UNIT 1: A massive basal unit comprising mafic to intermediate pyroclastic rocks including agglomerate, crystal and lapilli tuffs. The unit is pyritised and highly competent;
UNIT 2: A sequence of coarse rhyolite pyroclastic rocks associated with jasper, chert and fine grained tuff units. The top portion of the unit is characterised by coarse agglomerate with siliceous interstitial filling;
UNIT 3: Felsic to intermediate pyroclastic rocks. Highly carbonitised and silicified. Locally talcose, shearing and fractures associated with talcose lenses;
UNIT 4: Finely bedded volcaniclastic siltstone and gritstone with minor tuff and carbonate beds. Minor gypsum stringers;
UNIT 5: Coarse volcaniclastic rocks with large volcaniclastics in a carbonitised matrix.
The Al Amar deposit is cut by numerous intermediate to mafic dykes that are believed to post date mineralisation. A prominent dyke ranging from 10m to 20m in width with a north-south (mine grid) strike and a 60° east dip separates mineralisation to the east and west. Displacement along the dyke is reported at 1m to 2m.
The main mineralization, North Vein Zone, strikes east-west and dips steeply south with a strike length of 550 metres to a depth of 350 metres. Mineralization remains open laterally and at depth but a fault truncates the mineralized zone to the west. The zone is 10 to 45 metres wide, within which two vein systems have been identified, the hanging wall vein and the foot wall vein. These veins comprise a series of sub-vertical, discontinuous quartz veins up to 0.5 metres thick associated with sub-massive sphalerite and pyrite and minor chalcopyrite.
Summary:
Mining Operations assume using a fully mechanised long-hole open stoping method with subsequent backfilling using waste development. For the lower (<790mRL) levels of the mine the level spacing will be reduced from 30m to 20m and the mining sequence changed from a “bottom-up” approach to a “top-down” sequence utilising rib pillars for additional local and regional support. Access to the mine is by a new primary decline to the main production levels extending some 300m below surface to the 590mRL.
Processing Technologies
- Gravity separation
- Flotation
- Carbon in leach (CIL)
- Carbon in pulp (CIP)
- Carbon adsorption
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The process facility of Al Amar comprises a comminution circuit, a copper circuit, a gold circuit and a zinc circuit which produces copper and zinc concentrates for third party toll smelting and gold in doré form for third party refining. Ore processing involves crushing (primary through tertiary) in the comminution circuit to produce a blended ore which is then reclaimed to feed the copper circuit. The copper circuit comprises milling and flotation to produce a copper concentrate with the tails feeding the CIL gold circuit. Tailings arising from the gold circuit are then onwards processed in the zinc circuit by flotation to produce a zinc concentrate. Final tailings are then thickened and filtered prior to transportation by truck to a dry-tailings storage facility situated 1.2km north-west of the Al Amar Plant.
In the comminution circuit RoM ore from the underground operations is crushed in a three-stage crushing circuit comprising a primary jaw crusher, a secondary cone crusher and tertiary cone crusher operating in closed circuit. The crushing circuit reduces RoM ore with 300mm top size to -12.5mm and feeds the ball mill which further reduces the ore to 80% passing 75µm.
All slurry from the milling circuit feeds the copper circuit where copper flotation reagents are added to recover copper concentrates using froth flotation with rougher, scavenger and cleaner cells. Copper concentrates are then thickened, filtered and bagged (2t bags) for shipping.
Flotation tailings are then thickened and processed in the gold circuit where cyanide solution is added to dissolve the contained fine grained gold and silver in a six stage CIP tank. The precious metals are then absorbed onto activated carbon which is then screened from the pulp, washed and eluted with hot concentrated cyanide solution under pressure using a batch Zadra process. Precious metals are then recovered through electrowinning to produce precious metals sludge. This is then dried ahead of smelting in an induction furnace to produce 17kg to 20kg doré bars.
Tailings from the gold circuit feed the zinc circuit where zinc flotation reagents are used to recover zinc concentrates using froth flotation. Zinc concentrates are then thickened, filtered and bagged (2t bags) for shipping.
Final tailings are then thickened and filtered prior to transportation by truck to a dry-tailings storage facility.
Recoveries & Grades:
Commodity | Parameter | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 |
Gold
|
Recovery Rate, %
| 90 | 91.6 | 88.1 | 89 | 93.2 | 87 | 86.5 |
Gold
|
Head Grade, g/t
| | ......  | ......  | ......  | ......  | ......  | ......  |
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Production:
Commodity | Units | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 |
Gold
|
oz
| ......  | ......  | ......  | 44,029 | 48,411 | 45,288 | 52,531 |
All production numbers are expressed as metal in doré.
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Operational Metrics:
Metrics | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 |
Ore tonnes mined
| ......  | 250,060 t | 252,080 t | 252,550 t | 229,564 t | 202,170 t |
Waste tonnes
| ......  | 84,680 t | 72,240 t | | | |
Tonnes milled
| ......  | 255,987 t | 223,431 t | 215,229 t | 241,268 t | 208,888 t |
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Reserves at December 31, 2018:
Category | Tonnage | Commodity | Grade | Contained Metal | Recoverable Metal |
Proven & Probable
|
2.77 Mt
|
Gold
|
3.26 g/t
|
0.29 M oz
|
0.26 M oz
|
Proven & Probable
|
2.77 Mt
|
Zinc
|
3.96 %
|
|
|
Total Resource
|
5.2 Mt
|
Gold
|
4.02 g/t
|
0.67 M oz
|
|
Total Resource
|
5.2 Mt
|
Zinc
|
3.79 %
|
|
|
Commodity Production Costs:
| Commodity | Units | 2013 |
Cash costs
|
Gold
|
USD
|
355 / oz†
|
Selling price
|
Gold
|
USD
|
1,322 / oz
|
† Net of By-Product.
Financials:
| Units | 2017 | 2016 | 2015 | 2014 | 2013 |
Capital expenditures
|
M SAR
| | |
|
|
10.2
|
Revenue
|
M SAR
| ......  | ......  |
194.3
|
221.84
|
227.12
|
Gross profit
|
M SAR
| | |
|
|
150.46
|
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Corporate Filings & Presentations:
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Aerial view:
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