In my last blog post, I discussed an example of prolific energy waste in the platinum mining sector. In this blog, I’d like to explore industrial energy waste in the Copper Industry.
This case study is used to demonstrate the Business Case for Energy Productivity in the Copper Industry revealing savings of 46% energy cost savings and greenhouse gas emission reduction of 26,000 Tonnes.
The operation has several major energy users, one of these users is the converter blowers that provide medium pressure air to the copper convertors. The blower air is used to metallurgically process the molten 97% grade copper that is drawn from the furnace. It is then purified of its sulphur and iron content through the blowing process. This is an exothermic reaction, that consumed some 3.6MW of electricity 24/7 and it was assumed to be efficient. Coal was being used to stabilise the exothermic reaction when it was needed, and liquid fuel was being burned to stabilise the coal flame over the converter.
The operating cost of the system, was USD6,5 million per annum. Electricity costs for the converter blowers was around USD1.5 million per annum along with GHG emissions of 30,000 Tonnes. Liquid fuel consumption was 8 million litres per annum and coal consumption 10,000 tonnes per annum costing a further USD5 million.
Working with the engineering, technical and operations teams, the Ensight team implemented a change to the operating philosophy that would substantially reduce the excessive energy waste in the system. The testing of the energy saving interventions revealed a fault in the coal system that was present for over 15 years which had wasted some 3,000 tonnes of coal a year (over that 15 year period) as well as 3 million litres of liquid fuel per annum.
Through the implementation and testing of several energy saving interventions, the following achievements were made;
- electrical power was reduced by 70% from 3,6MW to 1MW;
- coal use was reduced by 30% from 10,000 tonnes to 7,000 tonnes;
- liquid fuel was reduced 37,5% from 8 million litres to 5 million litres.
Cost savings totalled USD2,69 million – made up of the following:
- electricity savings of USD1,1 million;
- coal savings of USD0,22 million;
- liquid fuel savings of USD1,3 million.
Total greenhouse gas emission savings from Ensight’s intervention on this system are 26,000 Tonnes per annum.
A total power equivalent of 8.8MW (combined electricity, coal and liquid fuel) was saved by Ensight without the need for capital investment. The project had a positive cashflow so the Internal Rate of Return (IRR) is not relevant and the Net Present Value (NPV) is USD22 million at 12% discount rate.
Prolific energy waste is all around you, one just needs to look.