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Tanzania
Williamson Mine

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 Location:
5 km NE from Kolandoto, Tanzania

  Regional Office:
Silver Point Office Park, Block 3, 22 Ealing Crescent, Bryanston
P.O. Box 71007
Johannesburg
South Africa
2021
Phone  ...  Subscription required
Fax+27-11-706-3071
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  • Overview
  • Owners
  • Geology
  • Mining
  • Processing
  • Production
  • Reserves
  • Costs & Financials
  • Personnel
  • Filings & News

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Overview

StageProduction
Mine TypeOpen Pit
Commodities
  • Diamond
Mining Method
  • Truck & Shovel / Loader
Processing
  • Crush & Screen plant
  • Jig plant
  • Dense media separation
  • X-Ray sorting
  • Grease belt/table recovery
Mine Life50 years (as of Jan 1, 2021)
16 November 2021 - The mine was placed on care and maintenance in April 2020 in order to preserve its liquidity, at a time when diamond pricing was impacted by the COVID-19 pandemic, and operations recommenced in Q1 FY 2022.
Latest NewsPetra Diamonds executes Williamson Diamonds MoU     December 20, 2021


Owners

Source: p. 22
CompanyInterestOwnership
Government of Tanzania 25 % Indirect
Petra Diamonds Ltd. 75 % Indirect
Williamson Diamonds Ltd. (operator) 75 % Direct
Williamson Diamonds Limited ("WDL") is the operator of the Williamson diamond mine in Tanzania that is owned 75% by PDL (Petra Diamonds Ltd.) and 25% by the Government of Tanzania.

On 13th December 2021 Petra Diamonds announced a new Framework Agreement in principle with the Government of Tanzania which will result in Petra’s share in the Williamson Diamond Mine becoming 63%, with the Government holding the remaining 37% share. This Framework Agreement will require Petra shareholder approval – the Circular for which will be published on the website once it has received approval from the UK’s Financial Conduct Authority.

Deposit Type

  • Kimberlite


Summary:

The mine is an open pit operation based upon the 146 hectare Mwadui kimberlite pipe, which is the world’s largest economic kimberlite to have seen continuous mining.

Despite having been in operation since 1940, the pit is only 95 metres at its deepest point due to the large size of the deposit. The low grade of the deposit is countered by the high value of its diamonds and lends itself well to high volume, bulk mining methods.


Mining Methods

  • Truck & Shovel / Loader


Summary:

The mine is an open pit operation based upon the 146 hectare Mwadui kimberlite pipe, which is one of the world’s largest economic kimberlites.

Despite having been in operation since 1940, the pit is only 105 metres at its deepest point due to the large size of the deposit. The low grade of the deposit is countered by the high value of its diamonds and lends itself well to high volume, bulk mining methods.


Crushing and Grinding


Processing

  • Crush & Screen plant
  • Jig plant
  • Dense media separation
  • X-Ray sorting
  • Grease belt/table recovery

Source: Subscription required

Summary:

Once a diamond operation yields ore, the diamonds must be sorted from the other materials. Excavated ore is transported to a processing plant.

The kimberlite is first crushed and then processed through the plant, which consists of a series of screens, jigs and scrubbers and a gravity pan or DMS plant to remove lighter particles and create a concentrate of heavy material, which includes the diamonds.

Diamonds are then extracted from this material by using an X-ray machine and/or grease table and checked by hand sorting. Most diamonds luminesce under X-rays and can therefore be identified and separated in final recovery. However, some diamonds – particularly more valuable Type II stones – do not respond well to X-rays, so grease tables are used to recover such stones. As diamonds are hydrophobic (meaning they repel water), they stick to the grease while the rest of the wet concentrate runs off.

The treatment of ROM kimberlite ore produces a sink (high den ........

Recoveries & Grades:

CommodityParameter202020192018201720162015
Diamond Head Grade, carats/t  ......  Subscription required  ......  Subscription required0.070.060.050.05

Production:
FY 2022 Guidance - assuming production restart in H1 FY 2022.

CommodityUnits202220202019201820172016
Diamond carats  ......  Subscription required ^  ......  Subscription required  ......  Subscription required341,102225,202212,869
^ Guidance / Forecast.
Subscription required - Subscription is required.

Operational Metrics:

Metrics20222020201920182017
Ore tonnes mined  ......  Subscription required
Tonnes processed  ......  Subscription required  ......  Subscription required5,495,470 t5,045,284 t4,071,592 t
^ Guidance / Forecast.
Subscription required - Subscription is required.

Reserves at June 30, 2021:
Resource bottom cut-off: 1.15mm.
Reserve bottom cut-off: 1.15mm.

CategoryTonnage CommodityGradeContained carats
Probable 48.6 Mt Diamond 0.069 carats/t 3.36 M carats
Indicated 63.4 Mt Diamond 0.049 carats/t 3.08 M carats
Inferred 958 Mt Diamond 0.036 carats/t 34.77 M carats
Total Resource 1,021 Mt Diamond 0.037 carats/t 37.86 M carats

Operating Costs:

Units202020192018201720162015
Total operating costs ($/t milled) USD 10.211.110.711.61112

Financials:

Units2022202120202019201820172016
Capital expenditures (planned) M USD  ......  Subscription required
Capital expenditures M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required4.6   15   24.4  
Revenue M USD  ......  Subscription required  ......  Subscription required  ......  Subscription required68.5   58.4   78.9  
Subscription required - Subscription is required


Heavy Mobile Equipment:

Mine Management:

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Oct 26, 2021
....................... Subscription required ....................... Subscription required Subscription required Oct 26, 2021
....................... Subscription required ....................... Subscription required Subscription required Oct 26, 2021
Subscription required - Subscription is required.

Staff:

EmployeesContractorsTotal WorkforceYear
Subscription required Subscription required Subscription required 2021
Subscription required Subscription required Subscription required 2020
Subscription required Subscription required Subscription required 2019
Subscription required Subscription required Subscription required 2018
Subscription required Subscription required Subscription required 2017
Subscription required Subscription required Subscription required 2016

Corporate Filings & Presentations:

DocumentYear
................................... Subscription required 2021
................................... Subscription required 2021
................................... Subscription required 2021
................................... Subscription required 2021
................................... Subscription required 2021
................................... Subscription required 2020
................................... Subscription required 2020
................................... Subscription required 2019
................................... Subscription required 2019
Annual Report 2018
Sustainability Report 2018
Annual Report 2017
Sustainability Report 2017
Annual Report 2016
Sustainability Report 2016
Project Description 2003
Subscription required - Subscription is required.

News:

NewsDate
Petra Diamonds executes Williamson Diamonds MoU December 20, 2021
Petra Diamonds Limited: Framework Agreement in principle with the Government of Tanzania December 13, 2021

Aerial view:

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