Privately-owned Swedish company Africa Resources AB is on the cusp of recovering significant diamond volumes from the diamond-rich Tshikapa region in the Democratic Republic of Congo.
This is thanks to the purchase of a newly designed and modern dredging machine that will effectively and safely pump diamond-bearing gravel from the Tshikapa River that falls within the company’s 75% owned concession explains CEO/CFO Thomas Häggkvist.
This article first appeared in Mining Review Africa, Edition 4 2018
Africa Resources AB’s establishment and strategic direction is an interesting one – born out of Häggkvist’s interest in acquiring a diamond concession from his former Swedish employer IGE Resources who in 2013 chose to exit from the DRC to focus on its nickel assets in Sweden.
The license was floating in the local subsidiary without a parent as that company was liquidated, until 2014 when Häggkvist took it over.
IGE Resources was involved in exploration and early stage mining projects in Scandanavia and Africa and invested into the diamond sector in Angola and then the DRC after purchasing AIM-listed Pangea Diamond Fields in 2010.
Häggkvist was the company’s first employee to visit the DRC concessions in 2012 together with his now local partner Clement ‘Papa’ Leta – a Congolese national who has been recovering diamonds in the Tshikapa region since the early 1990s using small-scale pumps and shovels.
“The volumes of carats Leta’s teams were producing by hand was phenomenal and I quickly saw the potential for larger-scale activities to recover greater volumes of diamonds.”
Häggkvist acquired IGE Resources’ 674 concession and established Africa Resources AB in 2014 in partnership with Leta, who owns 25% together with related parties on the concession and brings a wealth of expertise to the operation as well as solid relationships with strategic role players in government.
The 674 concession, which Africa Resources AB is entitled to explore and mine for 30 years, measures 36 km² in size and encompasses about 6 km of the Tshikapa River.
It is situated in the south eastern part of the DRC, no more than 15 km from the Angolan border.
“This is one of the most diamondiferous areas in the world,” Häggkvist highlights.
The Tshikapa River flows through the concession from south to north, and originates from the diamond-rich areas of Lunda Norte in northern Angola, passing a number of big diamond deposits and producing mines along its stream.
The river in some points is up to 100 m in width and averages between 3 and 10 m in depth.
To date, Venmyn Deloitte has confirmed a NI 43-101 compliant resource of more than 2.4 million carats at around 0.24 carats per cubic metre from an estimated 9.9 million cubic metres of gravel.
The concession was explored and documented historically by Pangea Diamond Fields including historical investments in exploration, resource estimate documentation, infrastructure and camp facilities.
“The information we have on hand pertains to the river terraces and these areas require more heavy-duty mining to recover the diamonds. For now, we are focusing on the river from which we can recover the diamonds with simple panning techniques initially.”
Venmyn Deloitte has also supervised gravel washing from the river on a spot covering what is commonly referred to as a ‘pot hole’ and determined an average grade of as many as 145 carats per cubic metre.
The monitoring covered a limited volume though, in total about 6 cubic metesr (142 bags of gravel).
One bag contained more than 1 carat per kg.
The optimal and most profitable recovery of diamonds from the river is largely dependent on consistently dewatering large volumes of gravel and Africa Resources AB has invested in modern, cutting-edge technology that will not only deliver on tonnages but also on safety.
Introducing the iDredge
Africa Resources AB enlisted the assistance of Imilingo Mineral Processing – a company established in 2015 who defines itself as a specialist in providing the most advanced sorting technologies, specifically X-Ray transmission (XRT), in conjunction with minerals processing solutions.
Having visited the site in late 2016, Imilingo MD and mechanical engineer by profession Jaco Prinsloo took Africa Resources AB’s strategic directives to the drawing board and designed a fit-for-purpose dredge at its offices in Centurion, Pretoria.
Prinsloo can be considered an expert in both diamond processing and XRT more specifically.
Prior to joining Imilingo, he worked at DRA as the lead project engineer at Lucara Diamond Corp.’s Karowe mine in Botswana.
He was in charge of incorporating an XRT circuit into the process plant which has successfully been operating since 2016.
“Having learnt during that process how to integrate XRT machines into the diamond process, I was then deployed to assist in the design of the recovery area for Stornoway’s Renard diamond mine in Quebec, Canada which also includes an XRT sorting machine,” Prinsloo notes.
The 6 x 6 m modular Imilingo iDredge consists of a 60 kW submersible pump and high depth compensators housed within a pontoon structure.
The pump is designed to accommodate 200 m³/h, with between 0 and 60 mm-sized particles pumped through a 150 NB pipe.
The pump is suspended from a rotatable crane structure, which also functions as the lifting equipment for maintenance tasks.
The pump was supplied by Tsurumi Pumps Africa and can operate at depths of up to 45 m.
Once the gravel is pumped to surface and piped to the riverbed, it will be sorted by hand – for now.
An on-board control panel enables the operator to determine the position and movement of the iDredge and the pump is driven electrically via a cable from the river bank.
The genset will provide power to the dredge and sizing screen and will be situated on the river bank but can also be housed in the pontoons for greater mobility.
Ribs on the dredge’s exterior provide stiffness to the structure which is manufactured using 3CR12 corrosion resistant steel – designed to prolong the life of the dredge.
Finite element analysis was also undertaken during the design of the machine to ensure structural integrity.
“The iDredge is a substantial improvement on current dredging/barging processes – specifically with regards to the incorporation of modern operating techniques and increased safety.
"Traditional barges in the region are equipped with centrifugal pumps and suction hoses which are used by underwater divers to transfer the material to surface.
"This equates to slow and unsafe procedures and in many instances divers are unable to reach the depths where heavier and therefore larger diamonds can be found,” Prinsloo outlines.
Africa Resources AB for example is initially targeting a pothole in the river which could extend well below 25 m in depth and are likely to deliver diamonds in excess of typical carats recovered from shallower areas.
The iDredge also offers the benefit of being easy to transport and can be collapsed, transported via containers to site, and then quickly re-erected.
The iDredge designed for Africa Resources AB has already been transported to the DRC and discussions are underway to determine how best to move the machine to the concession.
Having already journey over 1 000 km on ill-maintained roads from the Matadi port via Kinshasa towards the Tshikapa region, it needs to travel a further 70 km to reach the concession and this road cannot, in particular during the rain period easily accommodate heavy-duty trucks carrying the dredge containers.
“We will devise a solution to overcome this challenge. It is an immediate priority,” Häggkvist notes.
Greater plans on the horizon
Considering Leta’s operations to date have been recovering several hundred carats a day – more than some well-established diamond miners – the potential to recover well in excess of this using the iDredge is well within the realms of possibility.
Beyond this, a next step/phase 2 action plan entails the incorporation of an XRT sorter on site – likely a Tomra sorter which Imilingo and Prinsloo in particular is in favour of having worked extensively with the technology from his Karowe days to date.
“This would streamline the operation further and enhance our security on site,” Häggkvist also notes.
On the back of successfully introducing the first iDrege to the Tshikapa River, Häggkvist would like to introduce multiple dredges across various rivers and perhaps thereafter even look to mine the terraces using traditional earthmoving machinery.
The sky is really the limit.
Additional concessions, additional diamonds
Africa Resources AB has a contract with the owner of another license in the Tshikapa region – concession 665 - granting the company the right to produce diamonds from targets derived as a result of exploration carried out by Africa Resources AB on the riverbed.
The license is located adjacent to license 674 and has produced large quantities of diamonds also using dredging operations.
Experienced grades based on river bed gravel averaged 88 carats/t during an independently monitored and verified dredging operation in 2012.
The concession is 8 km² in size and has an NI 43-101 compliant resource containing 988 000 carats (inferred resource) within an estimated 6.5 million cubic metres of gravel.
Further to this Africa Resources AB has a 75% profit share of diamonds produced by Leta on targets identified by Africa Resources exploration activities.
It would also like to increase its concession ownership in the DRC to build scale to its production in time.