Chrome
Machadodorp
In 1971 Feralloys Limited a wholly-owned subsidiary of Assmang, expanded and erected a ferro-chrome smelter at Machadodorp for the production and export of charge and low-carbon ferrochrome. After a major reinvestment and expansion programme the Works now has a ferrochrome capacity of 300 000 tons pa. The works has ISO 9000 / 2000, OSHAS 18 000 and ISO 14000 / 2004 certification.
Raw Materials
| Ore: | The modern Dwarsrivier Chrome Mine, located 140 km from Machadodorp, supplies quality lumpy ore and concentrate to meet most of the Works' ore requirements. Some ore is also currently purchased from the Nkomati Mine, belonging to Lion Ore which is close to Machadodorp. |
| Reductants: | All reductants are sourced locally. These include coke, char and metallurgical coal. |
| Flux: | Quartz and limestone are supplied under contract by local quarries. |
| Handling: | A highly automated materials handling system distributes the raw materials to the four furnaces. |
Pelletising
The metallurgical concentrate , together with recycled baghouse dust are pelletised using Outokumpu technology. The pellet production capacity is 350 000 tons pa. Pellets substantially improve furnace production and efficiency.
Furnaces
Using computer-based mass balances and automated batching systems, the raw materials are blended into a charge suitable for each of the furnaces. The blend varies depending on the ferrochrome specification required.
The furnace operations consists of two open 33 MVA , one open 30 MVA (all of Tagliaferri design) and one closed 54 MVA submerged arc furnace (Titaco) with pre-heater (Outokumpu). The combined capacity is 290 000 tpa of charge chrome.
Slag-free ferrochrome ingots are produced by bottom ladle teeming. All slag and ladle skulls are cooled and sent to the Metal Recovery Plant to produce saleable ferrochrome products.
Metal Recovery Plant (MRP)
Ferrochrome production results in a discard slag, which contains entrapped ferrochrome metal. This ferrochrome can, however be recovered in the metal recovery plant which has an installed capacity of 20 000 tons of saleable product per annum.
The slag and skulls which are recovered by excavator and front-end loader, are crushed and screened into 10 x 3, 3 x 1 and -1mm size fractions. Batig and Delkor jigs are used to separate the metal from the slag in the coarser fractions while spirals are used to separate the -1mm material.
The waste slag is returned to the slag dump after hexavalent chromium neutralization.
Crushing And Screening
The three stage crushing and screening plant is automated and closely controlled to ensure that the ferrochrome complies with customer size requirements. The plant is operated in campaigns to crush products with different silicon specifications. All products are weighed and stockpiled according to size and silicon specification.
Products
| Furnaces | MRP | ||||
| Size: | To customer specification | Sizes: | 10 x 3 mm, 3 x 1 mm, -1 mm | ||
| Si: | 3 % to 6 % | Chemistry: | Not guaranteed, typical only | ||
| Cr: | 51.5 % to 52.5 % typical | Slag content: | 2.5% max for 10 x 3 mm, 10% max for 3 x 1 mm and 15% max for -1 mm. There is also a 15% max 10 x 3 mm middlings product. | ||
| S: | 0.060 max (0.04 typical) | ||||
| P: | 0.030 max (0.023 typical) | ||||
| C: | 6.3 % to 8 % | ||||
Safety, health, environment and quality
Safety
Machadodorp Works has had OSHAS 18 000 certification since 2003.
Health
Afrox Health Care is contracted to monitor and manage the health care programme. This consists of pre-employment, annual and termination medicals. An accredited external company monitors exposure to hazards such as noise, dust and chrome emissions. Results are used to improve protective equipment and operating standards.
Environment
The Machadodorp Works is ISO 14 000 accredited since 2001 and operates to a standard that is considered a benchmark in the industry.
The works is situated in a pristine environment with trout fishing downstream of the works. It has a licensed slag dump and is a zero effluent site. Storm water is captured via concrete channels to storm water dams. The storm water and process water are recycled to the plant. Boreholes around the works and from the river streams are analysed on a regular basis to ensure that the pristine environment is maintained.
The Environmental Management System monitors and manages risk in the areas of air, ground and water pollution to minimise the impact the operations have on the environment.
All furnace waste gas systems are duplicated to ensure superior operating availability. Taphole fume extraction improves conditions for employees. All waste gas scrubber effluent is contained, treated and the water recycled. No slimes dams are used.
Extensive training programmes create workforce awareness of environmental responsibilities.
Quality
An ISO 9000 / 2000 listed operation, Machadodorp Works takes pride in the quality of its products. To ensure that the product meets customer expectations all raw materials are closely monitored both on receipt and during use. Mass balances are used to ensure the furnace ingot product complies with specifications. Each furnace tap is separately sampled and analysed with the ingots only allocated to a stockpile once the analysis is known. The crushing plant operates in campaigns to handle the different products separately. Each shift's production is sampled and analysed prior to being placed on a final product stockpile.
All products are carefully checked both on dispatch and again at the harbour during loading.
A modern laboratory equipped with ICP, XRF, XRD and wet chemical facilities ensures accurate chemical analysis.
Human resources
The Machadodorp Works has developed a modern multi-skilled work structure and extensive multi-media training systems are in place to develop ABET, knowledge and skills throughout the workforce. Wherever possible local communities supply the resources required.
Organised labour and other stakeholders are represented on various forums to facilitate participative management. This ensures transparency, common purpose and understanding.
The company takes a keen interest in the social development and upliftment of the community and this is reflected in the number of projects undertaken in the areas of education, welfare and recreation.