Tag Archives: Petra Diamonds

Emesent’s Hovermap aids ore pass decision making at Petra’s Finsch diamond mine

Highly accurate point cloud data sets from a Hovermap scan have allowed Petra Diamonds’ Finsch mine engineers to “see” the condition of ore passes for the first time and avoid an estimated five months and R5 million ($350,000) in remediation, Emesent says.

Finsch, in South Africa’s Northern Cape, uses ore passes and underground silos to transfer ore between levels or to redirect ore for load and haul to the surface. Blockages, hang-ups, overbreak or scaling can impact the structural integrity and result in extended downtime and significant remediation costs. Accurate imagery enables mine engineers to gauge the integrity of ore passes and plan timely and cost-effective remediation programs, according to Emesent.

Historically, however, scanning and mapping inaccessible shafts and voids has been a challenge for Petra.

The company’s management sought a means of obtaining accurate visualisations of underground voids, quickly and cost effectively, without endangering the safety of Petra personnel or contractors, Emesent says.

Petra management trialled the Hovermap multiple data capture methods with Emesent partner, Dwyka Mining Services, contracted to carry out multiple scans of an indoor stockpile, ore passes and vertical shafts, and a series of access tunnels and ramps.

Hovermap is a drone autonomy and LiDAR mapping payload. It uses the LiDAR data and advanced algorithms on-board, in real time, to provide reliable and accurate localisation and navigation without the need for GPS.

Dwyka spent a day on-site conducting a series of scans using Hovermap mounted to vehicles, a DJI drone, or lowered in a protective cage. Dwyka delivered point cloud data sets for Petra’s survey team to geo-reference and analyse, within 24 hours. It also provided visualisations of the ore passes, enabling the mine engineers to ‘see’ the condition of orepasses for the first time, Emesent said.

Alex Holder, Group Planning and Projects Lead at Petra Diamonds, explained: “We lowered Hovermap down ore passes, flew the drone into draw points and even scanned our shaft and ramps by fixing the scanner to one of our vehicles. The visualisation delivered exceeded all our expectations. The data captured in one ore pass saved us significant time and effort by confirming it was irreparable. That saved us millions.”

Using Hovermap led to an immediate decision to abandon plans to expend resources remediating a compromised ore shaft. This decision saved Petra an estimated five months and R5 million.

Heinrich Westermann, Mining Engineer at Petra Diamonds, said: “The ability to power and switch the Hovermap payload between the various applications meant that we were able to scan a considerable amount of the mine in one shift. Generally, this was either impossible and, if it were possible, it would take weeks to collect those datasets and months to see the final visuals.”

The data collected by Hovermap has become the basis of a data library for the site. It is augmented regularly and used to inform operational decision making by Petra’s mine planning and survey teams, according to Emesent.

Petra intends to deploy Hovermap scanning technology to map inaccessible locations at its other sites across Africa, Emesent says.

Petra Diamonds’ Project 2022 initiative provides bright spot in latest interims

Late last week, Petra Diamonds confirmed that its “Project 2022” initiative was fully operational at both mine sites and the group level.

This milestone, coming in the face of recent output disruptions and the suspension of the company’s production guidance following the outbreak of COVID-19, is worth a mention.

When announcing Project 2022 in July 2019, Petra said the initiative was targeting an initial $150-200 million of free cashflow over a three-year period from the company’s 2019 financial year (year ending June 30, 2019) to its 2022 financial year (year ending June 30, 2022).

An internal project team, led by former Cullinan diamond mine General Manager, Juan Kemp, was established to identify and drive these efficiencies. Petra also appointed Partners in Performance, a global management consulting firm, to support Kemp and the project team.

The focus of Project 2022 is mainly on improving throughput at the company’s operations – which includes the Cullinan, Finsch and Koffiefontein mines in South Africa and the Williamson mine in Tanzania. Cost efficiencies, strategic sourcing and one-off initiatives are also included in its remit, all of which are likely to be handled at the group level.

In the interim update at the end of last week, Petra said the work to date had entailed a structured assessment of the value drivers at each mine site.

It said: “All ideas are evaluated and identified initiatives are systematically structured with timelines, enablers and project plans for each.

“The implementation of the identified initiatives was firmly on track but has been significantly interrupted by the COVID-19 lockdown. When operations return to full capacity, focused steps will be taken to continue the initiatives to ensure the delivery of the expected benefits.”

While revenue fell in the nine months to the end of March 2020, Petra said production rose 2% in this period to just over 3 Mct. This demonstrated “the delivery of significant throughput benefits realised through the implementation of Project 2022, offset by the disruptions to production relating to Eskom load shedding during Q2 FY 2020 (December quarter of 2019) and the COVID-19 lockdown measures towards the end of Q3 (March quarter of 2020)”, it said.

In a February 2020 update (reviewing the six months to the end of December 2019), the company said Project 2022 remained on track to deliver significant cash flow generation, reaching an annualised rate of $50-80 million.

It added: “However, the operational cash flow benefits are being eroded by a weaker diamond market, due to the outbreak of the coronavirus, which has served to significantly reduce activity across the pipeline.

“In light of this continued market weakness, coupled with the impact of adverse product mix, the delivery of Project 2022’s cumulative cash flow target is expected to be delayed, resulting in the $150-200 million being revised to $100-150 million by June 2022.”

Despite this setback, in the six-months to the end of December 2019, Petra achieved a record half year of run of mine production – 7 Mt treated and 2.07 Mct recovered – as part of the Project 2022 efforts.

Specific ideas considered under Project 2022 within its mining operations include the shrinking of shift changes to increase the number of productive hours on LHDs by changing the blasting time and ensuring shift handovers happen efficiently; appointing a contractor to load over the weekends; improving LHD cycle time by reducing delays from refuelling, operational delays (eg large boulders) and unplanned maintenance; and implementing a new shaft shift structure to increase winder operating time and reduce the amount of time the LHDs have to stop loading due to full underground silos.

These mining ideas are complemented by a set of ideas in the plant, the company said.

This includes the optimisation and redesign of high-pressure grinding roll crushers; refurbishing and redesigning the rolls so they crush recycled material more effectively and reduce the recycle load of the milling circuit. This would allow a higher proportion of run of mine ore to be fed into the mills, it said.

The company also wants to develop best practices for operation of the mills; improving automated control and standardising operating procedures to allow for a more consistent operating performance and a higher overall feed rate.

On top of this, Petra is looking into accelerating its processing of historical high value “red tailings” to fill plant capacity.

Petra plotting diamond recovery at Finsch with new X-ray machines

Petra Diamonds says in order to help it better understand and prioritise an improved product mix at the Finsch diamond mine, in South Africa, all of the coarse diamond X-ray machines in the processing plant have been upgraded.

The move, aimed at increasing the probability of the recovery of high value large stones, came as the company reported a 29% drop in sales in the last six months of 2019 to $61.7 million, mainly due to the average value per carat decreasing 25% to $79.

Petra said: “Poorer product mix at Finsch is due to the depletion of the higher value overburden dumps, as well as fewer and poorer quality large diamonds recovered compared to historical averages.”

The X-ray machines in the final recovery plant are supplied by DebTech, a spokesperson confirmed to IM.

Petra also said that the X-ray machines in the bulk sample plant (pictured: credit Petra Diamonds) have been replaced with newer technology X-ray machines and are now being used to treat recovery tailings from the main plant to provide additional assurance around the efficiency of the recovery circuit.

The spokesperson said: “We have a new BV (Bourevestnik) machine also XRL (X-ray luminescence) in the bulk sampling plant acting as an audit/scavenging machine.”

The mine produced 1.8 Mct in Petra’s 2019 financial year to June 30, 2019.

Cullinan shines in Petra Diamonds’ first half results

The Cullinan diamond mine, in South Africa, led the way in Petra Diamonds’ first half fiscal year 2019 results, with run of mine (ROM) from the underground block cave up 30% year-on-year to 785,444 ct.

Petra’s overall group production rose 10% year-on-year to 2.02 Mct (1.84 Mct in H1 2018), while ROM output rose 13% to 1.9 Mct.

Cullinan’s ROM diamond production increased 30% to 785,444 ct, due to a 12% increase in ROM treated to almost 2 Mt, as well as a 16% increase in the ROM grade to 39.3 ct/ht. This increase in volume and grade was due to the continued ramp up of production from the C-Cut phase 1 and a reduction in ore mined from old areas with higher waste dilution, the company said.

During the period, production from the C-Cut phase 1 was largely concentrated in the south-western part of the footprint and, therefore, not representative of expected production associated with the full extent of the C-Cut phase 1 block cave, Petra said.

The third and final underground crusher was commissioned during December, delivering increased operational flexibility as mining progresses across the footprint of the cave, the company added. The new Cullinan plant is fully operational and meeting design parameters while normal optimisation is ongoing.

“Overall, Cullinan production increased by 37% to 832,026 ct (H1 FY 2018: 607,235 ct) with increased ROM production supplemented by the ramp-up of tailings production,” the company said.

The C-Cut phase 1 project is planned to contribute around 3 Mt this year, with a further 700,000 t to 1 Mt sourced predominantly from the CC1E mining area, as well as from other B Block tonnes. Steady state production of 4 Mt/y will be delivered from C-Cut phase 1 and CC1E from FY 2020 onwards, according to the company. At the same time as this, the ROM grade at Cullinan is expected to remain in the 38-42 ct/ht range from FY 2019 onwards. The company’s current mine plan has a life to 2030, but the major residual resources at the mine indicate that the actual LOM could extend beyond 2030.

Meanwhile, at the company’s Finsch mine (South Africa), ROM carat production was flat at 927,934 ct in the company’s first half. A planned winder upgrade was successfully completed during the period, which necessitated a planned shutdown from December 21 to January 4. Overall, Finsch production decreased by 9% to 947,424 ct due to the planned reduction in tailings production.

Koffiefontein’s (South Africa) ROM production in the half remained flat at 25,275 ct as the company was negatively impacted during the period from community unrest relating to municipal service delivery, operational challenges experienced relating to plant availability and a lower than planned grade recovered. Since the start of January, additional crushing capacity has been introduced to the plant, employee attendance has normalised and monthly production is expected to ramp up.

Williamson’s (Tanzania) diamond production increased 23% to 214,421 ct, mainly due to an 18% increase in the ROM grade recovered as well as a 4% increase in tonnes treated to 2.7 Mt. Petra said it remained in discussions with the Government of Tanzania and local advisers in relation to the overdue VAT receivables and a blocked diamond parcel.