10 May 2018
Publication: Engineering News
Date: 9 May 2018
By: Marleny Arnoldi
It is now expected that the mine and the plant will only be fully commissioned in August 2019, rather than the end of this year as previously expected.
“We had to look at our processes [at the mine]. The phosphate is embedded in silica and to get the phosphate out to the required concentration, you need a particular process, such as reverse osmosis, which works well for the most part, but it does not consistently get us up to the 30% concentration that we require,” said ARC CEO Johan van Zyl.
Therefore, ARC and fertilised feed minerals miner Kropz, which owns 70% of the mine, needs to augment the reverse osmosis process with an additional process, of which there are two or three options available.
Van Zyl noted that this is a common occurrence for phosphate deposits globally, so it is not a new issue that the mine came across.
“We have received proposals from experts in Australia, Israel and Canada, who have weighed in on how the process can be augmented.”
Much of the time lag up to August 2019 is owing to ARC and Kropz wanting to ensure the right processes are implemented, after which building or the acquiring of additional equipment will follow.
“It is not a major addition, but it will take time,” said Van Zyl.
Depending on the experts’ process recommendations, the cost will vary.
Kropz CEO Ian Harebottle commented that Reverse flotation will still be used to recover the apatite, but with some enhancements to the process being considered to support improved operating efficiencies in the longer term.
"Securing additional capital remains a priority. We are still confirming the proposed circuit modifications to ensure sustainable future production. Construction is anticipated to commence towards the end of 2018.
Various funding and investment options continue to be explored with a view to ensuring the best possible outcome for the project and all stakeholders," he added.
The Elandsfontein phosphate mine is located 12 km from Langebaan and borders the West Coast National Park.
Mining Weekly Online previously reported that the phosphate mineralisation is contained in the Varswater formation, with the phosphate occurring in phosphatised shell fragments and phosphorite pellets. The remainder of the deposit comprises silica sand and calcium oxide.
The operation will be limited to a fenced off area of 500 ha, which will contain the excavation area, the processing plant and the office. At any time, the open area of the mine excavation will be limited to 60 ha.
The sandy nature of the Elandsfontein deposit means that the phosphate can be upgraded without the significant crushing and milling requirements that are often associated with rock processing.
A major component of the project will be the processing facility and its associated infrastructure, with a design capacity to produce 1.35-million tons a year of phosphate concentrate.
Included in the process will be screening, classification, milling, reverse flotation, dewatering and product handling.
Tailings will be dewatered by belt filter before dry stacking.
Kropz, which has invested $120-million in its 95% complete Western Cape processing facility, is finalising the process plant design.
The boxcut has been developed and ore has been opened for what will be an estimated 15-year life-of-mine.
Mining Weekly Online previously reported that the access road to site, overhead powerlines and the water supply lines have been developed.
The plant has capacity to supply 1.35-million tonnes of phosphate rock into the market, with an important aspect of the concentrate being that it is very low in cadmium and heavy metals.
Minopex has been contracted to operate the plant, with associate company DRA Global being awarded the engineering, procurement and construction management contract.
VDM Transport has been contracted to haul the concentrate from the mine site to the deep-water Port of Saldanha, which is 50 km away and accessed by national freight routes.
Kropz has secured offtake agreements for all its production.
Many additional boreholes have been drilled across the resource and initial metallurgical sample testing returned from Tenova, in Israel, is positive.
Changes to the processing plant are likely to be minimal and the cost of implementing the required changes is being calculated with a view to getting back into production as soon as possible.
While this has been taking place, water has been continually pumped out of the aquifer for recharging downstream to draw down the water levels within the mining area.