• Data Access
  • Your Email  
  • Your Email  
Keep me signed in.
Forgot your password?
Close
  • Forgot Your Password?
  • Enter the email you signed up with and we'll email it to you.
  • Your Email  
Close
Back
MDO
Mining Data Solutions
  • Home
  • Database
  • Subscribe
  • Sign In
  • Sign In
Lesotho
Letseng Mine

This page is not tailored to
devices with screen width under 750 px.
 Location:
136 km NE from Maseru, Lesotho

  Address:
Letšeng la Terai Mine
Mokhotlong
Lesotho
Phone  ...  Subscription required
EmailEmail
WebsiteWeb
Additional Resources for Suppliers & Investors
Drill results over 30 g/t Au
Stay on top of recent discoveries.
Search drill results by commodity and grade.
Largest mines in the Americas
Mining and mill throughput capaciites.
Full profiles of select mines and projects.
Deepest underground mines
Shaft depth and mill throughput data.
Full profiles of select mines and projects.
Heavy mobile equipment
HME type, model, size and quantity.
Full profiles of select mines and projects.
Permitting and construction projects
Projects at the permitting or construction stage. Full profiles of select projects.
Mines with remote camps
Camp size, mine location and contacts.
Full profiles of select mines and projects.
Mines & projects in Lesotho
A list of country's mines and projects.
Full profiles of select mines and projects.
  • Overview
  • Owners
  • Geology
  • Mining
  • Processing
  • Production
  • Reserves
  • Costs & Financials
  • Fleet
  • Personnel
  • Filings & News

Thank you for browsing through mine profiles compiled by the Mining Data Online team.

Would you like to subcribe or schedule a Demo?
  • Name:
     
  • Company:
     
  • Position:
     
  • Phone:
  • Email:
  • Message:

Overview

StageProduction
Mine TypeOpen Pit
Commodities
  • Diamond
Mining Method
  • Truck & Shovel / Loader
Processing
  • Dense media separation
  • Magnetic separation
  • X-Ray sorting
Mine Life2036


Owners & OPERATOR

Source: p. 7
CompanyInterestOwnership
MGC Mining (operator)
Gem Diamonds Ltd. 70 % Indirect
Letseng Diamonds (PTY) Ltd. (operator) 100 % Direct
Letšeng Diamonds has two shareholders: Gem Diamonds Limited owns 70% and the Government of the Kingdom of Lesotho owning the remaining 30%.

Deposit Type

  • Kimberlite


Summary:

Letšeng's pipes are primary vertical kimberlite pipes. Such kimberlite pipes are characteristically carrot shaped in section and comprise volatile-rich, potassic, ultrabasic igneous rock. Kimberlite has an inequigranular texture which results from phenocrysts and xenoliths being set in a fine-grained matrix.

Letšeng consists of two kimberlite pipes, namely the Main Pipe and the Satellite Pipe (Figure 13). The pipes are hosted in unweathered basaltic lavas. Prior to mining, both pipes consisted of the following features, listed from surface to depth:

- a superficial upper organic layer of black cotton-soil, or sponge, with a thickness of less than 1.0m;
- a leached gravel, which either consists of a brown basaltic overwash (<5.0m thick on the Satellite Pipe and poorly developed on the Main Pipe) or a widespread leached white gravel. The white gravel in the immediate vicinity of the pipes carries kimberlitic heavy minerals;
- a soft, clayey, weathered and oxidised yellow-brown kimberlite known as “yellow ground”. It is typically 2.5m thick and contains many heavily weathered basalt xenoliths; and
- a soft blue-green, partially weathered kimberlite commonly known as “blue ground”. It is at least 20m thick on the Main Pipe, with the degree of weathering decreasing with depth. On the Satellite Pipe, the weathered kimberlite is 15m thick in the south, but very thin or absent in the north, with a relatively sharp lower contact with fresh (hard) kimberlite.

Letšeng's Main and Satellite pipes are primary diamond deposits in near vertical volcanic pipes. Kimberlite rock has a typical inequigranular texture which results from phenocrysts and xenoliths being set in a fine-grained matrix. Kimberlites are volatile rich, potassic, ultrabasic igneous rocks of highly variable mineralogical compositions. There are two distinct types of kimberlite, namely:
* Group I (basaltic kimberlites): These are olivine-rich monticellite-serpentinecalcite ilmenite kimberlites; and
* Group II (micaceous kimberlites): These kimberlites consist primarily of rounded olivine macrocrysts in a matrix of phlogopite.

Diamonds in the kimberlite are associated with both eclogite and peridotite sources, with higher diamond grades occurring in the eclogite xenoliths. Diamond grades are determined by several factors:
* the relative abundance and diamond content of the original mantle rocks (preserved as xenoliths) which contributed to the kimberlite magma;
* the degree of contamination (dilution) by barren country rock fragments; and
* the degree of gravity-controlled sorting.
Diamond mineralisation is present within the facies of both pipes. This section discusses the various facies present along with their potential for mineralisation (i.e. their potential diamond carrying capacity).

Letšeng's pipes are primary vertical kimberlite pipes. Such kimberlite pipes comprise volatile-rich, potassic, ultrabasic igneous rock. Kimberlite has an inequigranular texture which results from phenocrysts and xenoliths being set in a fine-grained matrix. The pipes are hosted in unweathered basaltic lavas. Both pipes represent diatreme facies of volcaniclastic kimberlite that has formed as a result of an explosive eruption and contact with the atmosphere. Diamond mineralisation is present within the facies of both pipes.

The Main Pipe is a cone shaped body tapering downward with depth from a surface projection measuring 540m by 365m in extent. The long axis of the pipe trends northeast. The surface expression covers an area of 17ha. The contact with the basalt, as determined by limited historical drilling, dips inwards at 83°. From surface mapping as well as surface and underground sampling, eight different varieties of kimberlite were originally recognised in the Main Pipe, namely the K1 to K8 facies, in the order in which they were mapped. For practical resource and mining purposes the facies were previously grouped into three distinct and easily recognisable facies namely, K1/KOther; K4; and K6. Then, in 2009, the K1/KOther facies within the Pipe was divided into the K North and K South facies. All recent modelling and sampling has been carried out using these facies as the basis.

The Satellite Pipe is an elliptical shaped kimberlite measuring 425m, along its NNE SSW axis, by 130m wide on surface. The surface expression covers an area of 5.2ha, including a large basalt raft. This lenticular basalt raft extends from the central area of the pipe to the southwestern end and is located immediately adjacent to the western sidewall near surface. The basalt raft tapers downward which results in an increase in cross-sectional area of the pipe with depth. Below the base of the basalt raft, the pipe is elliptical in plan, and tapers at 83°, in conformity with the eastern sidewall. The Satellite Pipe is comprised of at least two facies of kimberlite. Within these two major facies, gradual changes in the size and mineral content of the xenoliths are noted. These major facies, namely North Volcaniclastic Kimberlite (NVK) and South Volcaniclastic Kimberlite (SVK), can be identified in-pit and are used for resource classification and mining purposes.


Mining Methods

  • Truck & Shovel / Loader


Summary:

The two pipes, termed Main Pipe and Satellite Pipe, were originally 17 hectares and 6.5 hectares in surface area respectively before mining. The pits excavated into these pipes are now approximately 120 metres deep.

The two kimberlite pipes are mined using conventional open-pit mining techniques on a split shell design. The split shell concept was adopted to optimise waste stripping and enhance cash-flow. Major mining activities except blasting are outsourced to contracting companies. Drilling is done with Atlas Copco Rock L8 & L6 machines. The mine employs a mixed loading and hauling fleet comprising CAT 385C and CAT 390D excavators, together with CAT 777 rigid dump trucks for hauling waste and CAT 745 articulated dump trucks for hauling ore. The mixed fleet results from different ore and waste profiles during different stages of mine development.


Crushing and Grinding
Crusher / Mill TypeModelSizePowerQuantity
Jaw crusher
Cone crusher

Summary:

The ore is fed into the plants and crushed by means of a jaw crusher. The ore is conveyed to a scrubber where it is washed. Ore is then fed into the DMS or undergoes secondary crushing or tertiary crushing in the re-crush circuit, prior to feeding back into the DMS.


Processing

  • Dense media separation
  • Magnetic separation
  • X-Ray sorting

Flow Sheet: Subscription required

Summary:

Ore is processed through three treatment plants with an annual throughput of 6.5 million to 7.0 million tonnes and carat recoveries of 114 000 carats to 130 000 carats.

Letšeng operates two main kimberlite treatment plants, termed Plants No.1 and No.2, which together treat 5.7 million tonnes of ore per annum. An additional 1.3 million tonnes per annum are treated by Alluvial Ventures, one of the contractors. Production through Plant No.1 commenced in March 2004 and in March 2008 through Plant No.2 . Full production commissioning was achieved in record time at the end of the second quarter of 2008.

The flow-sheets of the two plants are similar, though small improvements were made to Plant No.2 based on what was learnt from Plant No.1. They are fed by a Primary Crushing unit (the PCA) that crushes raw kimberlite ore to boulders smaller than 200 millimetres. Each comprises primary, secondary and tertiary crushing, scrubbing, sizing and concentration of the different ........

Recoveries & Grades:

CommodityParameter20192018201720162015
Diamond Head Grade, carats/t 0.0170.0190.0170.0160.016

Production:

CommodityUnits202020192018201720162015
Diamond carats  ......  Subscription required ^  ......  Subscription required  ......  Subscription required108,513108,206108,579
^ Guidance / Forecast.
Subscription required - Subscription is required.

Operational Metrics:

Metrics202020192018201720162015
Waste  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required29,776,058 t24,010,847 t
Tonnes processed  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required6,646,098 t6,679,581 t
Ore tonnes mined  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required6,694,753 t6,508,806 t
Annual processing capacity  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
^ Guidance / Forecast.
Subscription required - Subscription is required.

Reserves at January 1, 2015:
The Mineral Resources and Reserves as at 31th December 2019 at Letseng mine are unchanged from Jan 1, 2015.

CategoryTonnage CommodityGradeContained carats
Probable 137.2 Mt Diamond 1.75 cpht 2.4 M carats
Indicated 179.2 Mt Diamond 1.75 cpht 3.14 M carats
Inferred 105.9 Mt Diamond 1.71 cpht 1.81 M carats
Total Resource 285.1 Mt Diamond 1.74 cpht 4.95 M carats

Operating Costs:

Units2019201820172016201520142013
Direct operating costs ($/t milled) USD 12.513.811.210.711.412.713.3
Total operating costs ($/t milled) USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
Subscription required - Subscription is required.

Financials:

Units20202019201820172016201520142013
Capital expenditures (planned) M USD  ......  Subscription required
Capital expenditures M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 71.6   59.2   67.2  
Revenue M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 236.36  
Operating Income M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required 114  
Pre-tax Income M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required  ......  Subscription required
EBITDA M USD  ......  Subscription required  ......  Subscription required
Subscription required - Subscription is required


Heavy Mobile Equipment as of November 25, 2020:
HME TypeModelQuantityLeased or
Contractor
Excavator ....................... Subscription required Leased
Excavator ....................... Subscription required Leased
Truck (dump) ....................... Subscription required 19 Leased
Truck (dump) ....................... Subscription required 14 Leased
Truck (dump) ....................... Subscription required 16 Leased
Subscription required - Subscription is required.

Mine Management:

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Nov 27, 2020
....................... Subscription required ....................... Subscription required Subscription required Nov 27, 2020
....................... Subscription required ....................... Subscription required Subscription required Nov 27, 2020
....................... Subscription required ....................... Subscription required Subscription required Nov 27, 2020
....................... Subscription required ....................... Subscription required Subscription required Nov 27, 2020
....................... Subscription required ....................... Subscription required Nov 27, 2020
....................... Subscription required ....................... Subscription required Subscription required Nov 27, 2020
....................... Subscription required ....................... Subscription required Subscription required Nov 27, 2020
....................... Subscription required ....................... Subscription required Subscription required Nov 27, 2020
Subscription required - Subscription is required.

Staff:

Total WorkforceYear
Subscription required 2019
Subscription required 2018

Corporate Filings & Presentations:

DocumentYear
................................... Subscription required 2020
................................... Subscription required 2020
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2018
Annual Report 2017
Annual Report 2016
Annual Report 2015
Annual Report 2014
Technical Report 2011
Subscription required - Subscription is required.

Aerial view:

Subscription required - Subscription is required.

Terms of Use Privacy Policy © 2020 MDO Data Online Inc.