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Venetia’s transition to underground mine about 54% complete, says De Beers

21st January 2022

By: Simone Liedtke

Creamer Media Social Media Editor & Senior Writer

     

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Diamond miner De Beers Group’s $2.2-billion Venetia Underground Project (VUP) is nearing 54% completion.

The VUP is designed to transition the mine from an openpit to an underground operation and, in so doing, extend the mine life by 23 years to 2046.

At steady-state production, 5.9-million tonnes of ore will be treated through the existing process plant to produce about 4.5-million carats of diamonds a year.

While the miner’s budget and targets were set before the Covid-19 pandemic, VUP project director Allan Rodel says the miner’s site team has “done a fantastic job” in recovering some of the losses experienced over the last two years.

The VUP is now targeting first production by late 2022 as it is tracking well against the post-Covid forecast. It is also expected to remain within budget.

However, over the course of the last 18 months, Rodel says, the VUP achieved a 280% improvement in mining development rates.

The miner is now targeting to double the development rates at the top-of-mine within the next 12 months, while the bottom-of-mine is targeted to double capacity within the next nine months. This, Rodel explains, will enable first production in the fourth quarter of 2022 and a ramp-up to full production from 2024 onwards.

First production at the VUP is targeted for December 2022, says VUP senior site manager Andre Trytsman.

The underground infrastructure comprises two vertical shaft systems for personnel transport, ore transport, routing of services, and lateral access to levels on the 54L, 91L and 94L stations for the services shaft and 100L station for the production shaft.

Once in operation, Venetia’s two kimberlite pipes (K01 and K02) will have fully transitioned from openpit to underground operations. However, the K02 openpit is already depleted and the K01 pit should conclude surface mining in late 2022, thereby accommodating a smooth changeover to the underground mine.

For now, both pipes at the VUP will be mined using a sublevel cave method.

K01 – a sizeable orebody measuring 550 m × 120 m – will be responsible for the bulk of production, generating an average of 3.5-million carats from about 4.5-million tonnes a year of material.

The K02 orebody – measuring 200 m × 300 m – will provide the balance, producing about one-million carats from 1.5-million tonnes to 2.5-million tonnes a year of material.

Both orebodies will be accessed through two vertical shafts, blind sunk to a depth of 1 065 m; however, there are indications that K01, in particular, extends well below 1 000 m, and De Beers may explore options that extend the underground operation’s life beyond 2046.

The service shaft has a finished internal diameter of 7 m and will eventually provide all the services and people transport to the underground workings, while the production shaft, also with a finished internal diameter of 7 m, will be fitted with two rock winders, each having two 24 t payload skips.

Both the service and production shafts will serve as downcast air intakes to the underground workings, while a decline and pit ramp will assist with early underground access for the construction of the production infrastructure for K01 and K02, which will be developed concurrently with the vertical shafts.

They will also serve as an additional air intakes and logistical access points, which the VUP says will mitigate the immediate requirement for the use of the shafts for ground handling.

De Beers contracted Murray & Roberts Cementation (MRC) to sink the shafts for the underground project. The contractor used what is now known as the presink gantry methodology.

Overall, the VUP will undertake 61.5 km of initial excavations as part of the expansion project, as well as a further 177 km of excavations over the remainder of the underground life-of-mine.

The surface infrastructure, which includes change houses, a heat tolerance testing centre, a lamp room, a proto room, a control room, winder houses, workshops, warehouses, ventilation systems and a state-of-the-art training facility, were completed last year.

Further, the miner said last year the use of technology was “critical in building the mine of the future and will ensure the safety of our people, as well as create unique employment opportunities”.

This was as a result of a technological collaboration between De Beers and engineering group Sandvik Mining and Rock Solutions, through which the successful implementation of technology “holds the key to further improve the mine’s productivity and cost effectiveness, enabling the quality and accuracy required for precision mining”.

The technology will also allow the miner to provide real-time geospatially referenced data that supports digitalisation of processes and provides a wealth of data for analysis and continuous improvement.

Training

Alongside the VUP’s transition is its ability to train and enable openpit employees to transition to underground employees.

So far, 136 employees have transitioned from the openpit to underground through VUP’s transition programme that assesses employees’ current and required skill sets and includes heat tolerance testing, and whether employees can work underground.

Internal programmes and training development also take place, as well as cultural transition programmes, which look to discuss how the employee will transition with an open mindset. This is heavily focused on new ways of work, Rodel says.

The process of transferring an employee starts with medical fitness screening and heat tolerance testing, after which a successful employee will be cognitively assessed before being released to an underground training facility.

The tailored training programme enables them to meet minimum compliance obligations for working underground and is in line with regulatory requirements.

Employees are further trained to acquire provisional licences prior to proceeding to practical training on trackless mobile machines (TMM), and those at supervisory level will be trained in line with Mining Qualification Authority (MQA) requirements for the relevant qualifications.

The underground project has added a yearly average of between 1 000 and 2 000 full-time job opportunities since its inception. This will, however, ramp down during the next four to five years as construction is completed.

The VUP is also in the process of implementing programmes to meet the housing needs of its employees, as well as providing skills development opportunities, including for new recruits from labour-sending communities.

Going Green

De Beers, an Anglo American Group subsidiary, is aiming to have Venetia mine operating as a carbon neutral mine by 2030. The use of battery electric vehicles (BEVs) and the installation of a 60 MW solar photovoltaic (PV) plant are expected to help achieve that goal.

The ultimate sizing of the energy plant is still to be finalised, Rodel notes.

This falls in line with De Beers Group’s goal of achieving carbon neutrality at its mines in Botswana, Canada, Namibia and South Africa, as well as at its other operations across the diamond pipeline around the world.

De Beers carbon neutrality head Kirsten Hund previously told Engineering News & Mining Weekly that the group aims to optimise energy efficiency across all operations, introduce clean-fuel equipment and green electricity generation, and ensure nature-based carbon absorption programmes.

At Venetia mine, specifically, Rodel explains that the 60 MW solar PV plant will largely be used for power generation during the day. Storage options will be considered later and will be aligned with the Anglo American regional and national programme.

There is also potential to expand the solar PV plant in future, Rodel says.

He adds that De Beers is finalising operational and funding models given the national/regional approach to alternative energy production. Construction will start once the study work and all permitting has been completed.

De Beers Group is also considering investing in wind farms in South Africa, to allow it to generate “a significant amount of energy” which it will then use at Venetia Mine through “wheeling” the electricity throughout the national energy grid.

De Beers Venetia Underground is expected to be a world-class operation, and, as a result, will be incorporating innovative and technologically advanced methods and systems to continue servicing the world’s diamond demand.

Edited by Chanel de Bruyn
Creamer Media Senior Deputy Editor Online

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