During the rapid growth of the ferro alloy industry in South Africa in the seventies, Mintek identified the need for recovery of metal from slags. Attempts by industry to use physical separation techniques such as DMS, spirals, table, magnetic rolls and diaphragm jigs proved inefficient and were often not cost effective due to low recoveries and poor grades of metal.
During the late eighties Mintek identified pneumatic jigging as the technology most suitable for metal recovery from ferroalloy slags. Initially a Batac jig was modified to achieve higher recoveries and grades of metal.
At about the same time Titaco became aware of the need in the market for better metal from slag recovery technology and approached Mintek with a view to developing a complete product / process package for the market.
The Titaco / Mintek joint venture grew out of this interaction. Since its formation in 1992 it has built eleven major metal from slag recovery plants in Southern Africa capable of processing between 120 and 200tph of slag. It has also constructed a 100tph plant for Sweden, a 60tph plant for France, a 50tph plant for Romania and has supplied 10 – 35tph mobile jigging plants to clients throughout the world. A reference list is attached.
The Titaco / Mintek technology has been developing ever since its inception. Initially, pneumatic jigs were only used to recover metal from coarse (+6 – 25mm) slag fractions while diaphragm jigs were used for fine (+1 –6mm) fractions.
The Batac jig was abandoned in favor of the Apic jig in about 1996. Apic jig is a development of the original Apic pneumatic jigs. FCB of France has sold the technology to Titaco. A description of the jigs is attached and a list of Apic jig sales is shown in Table 2.
Building on the advantages of the Apic jigs Titaco / Mintek have developed a fines (+1 –6mm) Apic jig to complement the coarse (+6 –25mm) jigs. Since 1998 the Apic fines jig is now standard on all Titaco / Mintek MRP’s and two of the major plants have been retrofitted with these circuits. Recently, a new device, the Apic classifier, has been developed for ultrafines and it was commercialised at Middelburg Ferrochrome in November 2000 and Transalloys silicomanganese in April 2002. It replaces spirals because it gives better recoveries and grades and is easier to operate.
Mining, crushing, screening, slimes handling and water reticulation form part of the process.
Slimes that are washed out on the screens, are removed by the desliming cyclone. After thickening the slimes are dewatered and the supernatant water is returned to the gravity separation circuit. All products of the process are managed in an environmentally safe fashion.
The process design has been based on success achieved and lessons learned from the many plants that the Titaco/Mintek JV have built in the past. It is a state-of-the-art solution to ensure optimum economic recovery of ferroalloys from the slag.
The process design is based on process development expertise, design and project engineering capability and Atoll’s extensive operating experience that lead to optimum capital and operating costs for high recovery of on-specification ferroalloy from the slag.
The success of the technology was recognized by the Associated Scientific and Technical Societies who awarded it their national trophy for ‘outstanding contributions to science or the application of science in 1999’.
As the MRP business developed it became apparent that many clients required a build own, operate (BOO) service rather than their own plant and Titaco / Mintek decided to form the Apic Toll Treatment (Pty) Ltd joint venture company (Atoll) to provide BOO services.
Today Atoll operate MRP plants at Transalloys, Vargön Alloys in Sweden, Middelburg Ferrochrome, Hernic Ferrochrome, SA Ferrochrome, International Ferro Metals, Zestafoni in Georgia, ASA Metals and has joint venture toll treatment operations at three other sites in South Africa, one in Brazil, one in USA, and one in Russia.
Atoll’s clients enjoy the benefit of the high recoveries of cost effective MRP plants which produce saleable coarse metal (<2% slag) at >95% recovery, saleable fines (<2% slag) at >95% recovery and ultrafines (<10% slag) at >70% recovery.
Ultrafine metal concentrates produced by Atolls MRP’s are usually not saleable. Although these concentrates are often recycled to clients existing ferroalloy furnaces, Atoll has been able to use Minteks patented DC arc furnace technology to remelt and refine such materials. Ulltrafine baghouse dusts and other ultrafine wastes from the ferroalloy industry present environmental and health threats. Mintek’s Enviroplas DC arc furnace technology converts these ultrafines into valuable ferroalloys. Atoll is using this technology at Mogale Alloys where a 40 MVA DC furnace produces a Fe, Ni, Cr alloy from stainless steel EAF dust and chromite fines. A photograph of one of the furnaces used appears on the front cover.
Titaco merged with Bateman in 2000 and in 2006 the AIM listed Bateman Engineering NV (BENV) bought Mintek’s share in the RSA part of the Atoll group and consolidated all the Atoll companies under the BENV mantle.
Jigging Technology Wins AS&TS Award
Mintek and Titaco Projects Ltd are the joint recipients of the Associated Scientific and Technical Societies of South Africa (AS&TS) 1999 national award for 'outstanding contributions to science or the application of science'.
The award, which was made for the development and industrial implementation of the modified pneumatic jigging process for recovering ferro-alloys from slag dumps, was presented by Professor Rosemary Falcon, President of the AS&TS, at the Association's annual award ceremony on 23 July.
This is the third time that Mintek has been honoured with this prestigious award. The first presentation, in 1986, was for Mintek's role in the development of the carbon-in-pulp process for gold recovery, and the second, shared with Samancor in 1995, for the DC-arc smelting of ferrochromium.
By adapting and modifying pneumatic jigs manufactured by French and German equipment suppliers, Mintek and Titaco have succeeded in recovering saleable metal at high yields from slag dumps that were previously uneconomic to re-process. Recovery plants using this technology are the cheapest source of ferro-alloys, and act as 'swing' producers - providing extra metal to meet high demand without the need for extra furnace capacity, and low-cost material when furnaces are shut down during market depressions.
Burgersfort
Late in 2007 Atoll commissioned an 80 t/h metal recovery plant (MRP) plant at Mashila Metal Recovery which is situated at ASA Metals near Burgersfort, South Africa. This was the first time that a truly Broad Based Black Economic Empowerment (BBBEE) venture has been launched in the MRP industry and it involves all the stakeholders and the local communities whom all benefit from the venture in the form of employment including direct financial benefit. Atoll’s direct investment into this venture is approximately USD 5 million.