EXTRACTING ADDED VALUE

When it comes to mine tailings disposal, Cyclone Engineering Projects is at the cutting edge

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On 25 January 2019, a tailings dam at the Córrego do Feijão iron ore mine, east of Brumadinho, Minas Gerais, Brazil, failed. The ensuing mudflow engulfed the town, killing 270 people in the process and dramatically shone a spotlight on the vital importance of doing mine tailings disposal properly. Leadership spoke to Gerrit Jansen van Ryssen, Managing Director of Cyclone Engineering Projects, a leading mine tailings disposal company, for more insight.

What is the importance of a mine tailings disposal system?

Any mine, no matter what they are mining, has residue to get rid of. In ±99% of mines, the residue is in a pulp or slurry, containing a large percentage of water that is pumped to a specially designed facility where it can be placed safely and finally rehabilitated. These facilities usually range from as small as 6ha to up to >1500ha in area. For instance, in the gold industry, apart from the non-gold bearing rock that is stockpiled close to the shafts, all the gold-bearing rock goes through the extraction process in the gold plant. The volume pumped to the residue facility varies from mine to mine.

The Tailing Storage Facility (TSF), to safely place this residue, is normally designed to be utilised for the life of the mine, which might be anything from 10 years to 50 years. The latest development is to design “mega” TSF’s varying from ±500ha to 2000ha. The reason is that many of the South African mines are reclaiming old slimes dams to recover gold left by old extracting technology, and large volumes are treated to be economical.

What are the particular benefits of cycloning?

A cyclone is a cone-shaped cylindrical device which receives slurry at a designed slurry density, volume and pressure from the pumping system at the plant. Due to centrifugal forces, the coarse and fine particles separate at a designed cut (or required particle sizes). The low-moisture coarse particles are used to create the TSF wall zone and the fine particles with the majority of water are discharged into the basin of the facility. Due to gravitational forces, the fine particles settle to create a beach effect and water flows to the lowest point from where it is decanted for reuse in the plant.

The patented vacuum system creates a vacuum in the cyclone, lowering the coarse fraction moisture content to less than 30%. This material is suitable for buttressing unstable TSF walls by means of downstream cycloning. Due to the low-moisture content, no drainage system at the toe of the facility is required. More water is recovered from the facility, enabling the mine to buy less freshwater from the authorities.

It is expected, after the disaster of the Valé mine in Brazil, that new global legislation for TSF design will force mining houses to construct all new TSFs only by means of downstream and centreline deposition. Cyclone Engineering Projects (CEP) is the leader in the proposed deposition method by either conventional or vacuum cycloning techniques.

What was your introduction to cycloning?

This is a long story that emanates from my days working at a phosphate mine called Foskor in Phalaborwa from 1981 to 1993. Tailings disposal, and everything involved in tailings, such as the total environmental issues, were of real interest to me. I took the opportunity during this time (apart from my normal duties) to head the construction of a new 1000ha Tailings Storage Facility (TSF). Certain sections of the construction were done in-house, with a very specialised team under my supervision.

The outside world was calling and I joined the largest company in the country, specialising in the managing and operations of TSFs. My knowledge in cycloning brought a lot of opportunities into this company, specifically after the disastrous failure of the Merriespruit slimes dam, during 1994, at Virginia in the Free State. It is common knowledge what the consequences of that failure were. The failure was rectified by utilising my cyclone knowledge on tailings/slimes, and it took a mere 11 months to close the wash-away caused by the failure in the wall.

With normal methods (even mechanical methods) it would not have been possible, but it was found that with cycloning, at a rate of rise of up to 11m per year, it is safely achievable. I introduced many sites to cycloning, specifically where sloughing of TSFs took place. This was done with great success. I left this company after four years as Operations Director when I saw the opportunities in my field of expertise.

When did you establish your own company?

Due to a so-called restraint of trade, I joined Anglo American Corporation at their Technical Services for 12 months as an engineer with the focus on surveillance on TSFs. I played open cards with my employer and told them that I would be registering my own company on completion of the 12-month period they offered me. My aim was to consult in the mining industry on the design of cyclone-operated TSFs, train the operators and compile all operating manuals, etc. At that stage, cycloning was not a well-known method of slimes/tailings depositing.

During this period at Anglo American, I had the opportunity to be part of one of Debswana’s new plant and slurry dam facilities and a difficult new TSF in Mali. These two projects opened the doors for my dream to establish my own company, and Cyclone Projects & Consulting (CP&C) was established in September 1998. Great success and growth were experienced; I consulted and designed all over Africa and South Africa, specifically on cycloning and cyclone operations for the mines and the majority of civil engineering consulting companies involved in the design of TSFs. CP&C developed the cycloning techniques for basically the total spectrum of minerals.

During November 2007, on request of some of the mining houses, Cyclone Engineering Projects (CEP) was established as a sister company of CP&C, whose focus is on managing and operating TSFs and the reclamation of old gold-bearing slimes dams for the recovery of gold from it by the gold plants. Today CEP has a black-owned company with a 26.2% shareholding, while our Operations Director owns 10% of the shares. CP&C has the balance of shares in CEP.

What is CEP’s role in the mining value chain?

The most important thing is to ensure that the TSF is operated and managed in such a manner that there is no risk to the mine. A serious problem due to bad operations might bring operations to a halt, which might take weeks to rectify before it is declared safe for mine operations to continue. TSFs are a direct cost to the mine, and the only real value is the quantity and quality of water returned from the facility to the plant. Reclaiming old TSFs plays a major role in the survival of many mines, where the valuable minerals still in the tailings dams are economically extracted. The construction of mega TSFs to deposit slimes from smaller old dams lowers the rehabilitation cost for mines, and the land is cleared for future industrial development.

What additional services have you added to your offering since 2007?

Hydraulic mining (or reclamation) of old mineral-bearing dams has become a major part of our business, and within the past 12 months, two contracts were awarded to us. High-pressure self-propelled remote-controlled water guns are used to re-pulp the slimes in a well-managed manner and pump them to the plant to recover the remaining minerals.

With regards to civil construction, CEP undertakes all required civil work necessary to ensure a safe and stable TSF for the client, under the control of our qualified civil engineer. Typical civil works are the sleeving and grouting of decant penstock towers, installation of new “floating” penstocks where the existing penstock either failed or reached its safe design height, installation of elevated drainage systems to lower the phreatic surfaces in order the ensure a stable wall zone, concrete lining of trenches and other small civil works required or requested by the client.

What is your approach to client service?

Client service is of the utmost importance. You know your client’s requirements and they should know who to contact or talk to any time of the day. I believe in eye-to-eye contact with my clients where we can sit down and discuss any issues which may pose a risk. Informal discussions over a cup of coffee are important to show that we value the client’s needs and requirements. We, furthermore, have formal meetings and discussions with our clients on a monthly or quarterly basis, where accurate minutes are recorded.

To improve overall service quality, continuous training and coaching by the management team and supervisors, ensure that management knows what the company needs and what should be implemented. The career path should also be clear to all. High performers are acknowledged in a reasonable manner. The fact that the opposition companies are continually trying to headhunt our employees is a good sign that we are on the right track with our staff.

How would you describe your leadership style?

Hands-on, supportive and I lead by example. Communication in all directions ensures an informed workforce. My office door is always open and any employee who has a problem is welcome to discuss it in person with me.

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