Limpopo-based copper miner Palabora Mining Com- pany reports that since the implementation of its converter blower project, the company is saving an average of 2.19 MW in energy. The project is expected to save Palabora in excess of R8-million during the first year of operation.

The project was approved as part of a suite of energy-saving projects that constitute the company’s energy leadership programme, an ongoing energy-saving effort developed in conjunction with energy efficiency firm Ensight, which specialises in energy-intensive industries.

“The smelter energy leadership team started to investigate the project in November last year and State-owned entity Eskom’s project evaluation committee approved the project for Stand-ard Offer Programme (SOP) funding in February,” says smelter technical manager Claude Schaba. He adds that the converter blowers project represented one of the most significant opportunities to save energy on site.

Smelter maintenance engineer Pierre Terblanche notes that owing to the nature of the changes required to execute the project, the converter blowers project was recognised early in the programme as a quick-win project that could produce large savings.

Smelter technical superintendent Ruan Fourie explains that there are three converters located in the smelter section. “In the converters, air is introduced by the converter blowers to react with the iron and sulphur in the matte. “The oxygen reacts with the matte to form a fayalite slag, which contains the iron, and sulphur dioxide (SO2). The fayalite slag is skimmed off while the SO2 is transferred to the acid plant to produce sulphuric acid, a production by-product.”

“Previously, the blowers were operated continuously, regardless of production. An opportunity was identified to reduce energy use by matching the operation of the blowers to the needs of the process,” he notes.

Ensight project engineer Ian Mulder notes that the project underwent various testing phases to confirm and optimise the control design. Once implemented, the project’s actual SOP performance was measured and verified in June by an independent Eskom-appointed measurement and verification team.

The project was executed in two phases.

“In the first phase, the operation of the blowers was manually changed to meet process demands. “This means that a blower runs only when its converter is in operation and production demands air supply.

“In the second phase, programming changes were made to the blowers’ control system. This involved improving the guide vane control of each blower, reducing the average operational load of each blower. As the process demands change, the blower’s guide vanes adjust accordingly to ensure that unnecessary load is not placed on the blower’s motor,” Mulder explains.

He adds that the project reduces the cost of copper production in the smelter section, owing to the reduction of the amount of energy required to produce one unit.

“This project involved implementing control procedures and systems to achieve energy and cost savings. Often, on large industrial sites, with complex operational systems, operational processes are put in place based on the various situations.

“Owing to the dynamic nature of industrial sites and processes, the operational procedures require updating on a regular basis, but process energy optimisation is often overlooked,” Mulder states.

He points out, however, that the response to the project from the smelter operators and leadership team has ultimately made the project a success.

“Once the converter and converter blower operators became aware of the cost of energy, they worked extremely hard to realise reductions” says Johan Kleyn-hans, power plant specialist where the blowers are situated.

Mulder notes that costs were incurred in engaging specialists to determine the optimized control philosophy, as well as in directing human resources toward project facilitation, change management and stakeholder engagement.

“The first milestone was to reach an agreement between stakeholders that the project would not adversely impact on production, safety or environmental performance. “The process required addressing the concerns of all parties involved, detailed investigations, stakeholder presentations and technical and business reviews,” he says.