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Technical Information

Charging The Skip

Raw materials

The plant requires five raw materials: copper ore, coke, limestone, iron stone and water.

The copper ore available in the immediate area and from nearby locations is a mix of cuprite (Cu₂O, Copper I Oxide), native copper and malachite. While the ore’s copper content can vary between 15% and 45%, an average content of 27% will be used in the processing.

Process

The coke acts as the furnace’s fuel and as a reducing agent. The form of coke required for the plant is not available locally but can be sourced from South Africa, China, India and Zimbabwe. The importing of coke implies a lag period of 2 months.

Limestone and iron stone are reagents used as fluxes; both of which readily available locally.

The running plant requires 100,000 liters of water per day, for cooling purposes. It currently has storage facilities for 240,000 liters, which can be easily replenished on a daily basis.

Table A below, illustrates the quantities required and costs incurred to produce 1 metric ton (94% - 97% purity) of black copper:

Raw material

Quantity

(metric tons)

% relative to Copper ore

Material Cost

(US$ per metric ton)

Final Cost

(US$ per metric ton)

Copper ore

4.7

-

-

-

Coke

1.5

33%

-

-

Limestone

1.2

25%

-

-

Iron stone

1.6

35%

-

-

Operational costs

-

-

-

-

Fixed overhead costs

-

-

-

-

Total production costs

-

-

-

-

Table A: Raw materials

Table A assumes that the copper ore has 25% copper content.
If this content reduces, a larger quantity of ore would require smelting in order to produce the same quantity of output black copper. This further implies a larger quantity of coke to successfully perform the smelting.
Similarly, a higher grade of copper ore would require smelting of less ore and coke to produce the same output quantity of black copper.
The optimal copper ore content is above 25%.
It should be noted that it is technically feasible to mix different batches of ore, for instance 40% - grade ore can be mixed with 22% - grade ore, to achieve the ideal quality of ore.
Note that costs have been omitted due to their direct relationship with constantly fluctuating economic factors that are prevailing at the time

A by-product from the processing is 8 metric tons of a nonferrous slag, also known as scorry. This slag can be in the road construction and cement industries. However, there is no local market for this by-product and it therefore has to be disposed off from the plant on a daily basis. Approximately 2% of black copper produced is lost into the formation of slag.

Maintenance policies

The plant requires 7 days of down-time after every 21 days of processing, in order to carry on with a second campaign of production. This equates to roughly 3 production campaigns and a 21-day downtime within a period of 90 days. Following the same schedule, this implies that in a year, the plant can be in production for 9 months.
Major rehabilitation activities must be undertaken on the furnace every 5 years. All other non-current assets, such as motor vehicles and forklifts, require replacement every 3 years.