The demand for more effective and efficient impeller and agitator technology is greatly increasing throughout Africa, where mining developments and mineral exploration are constantly budding, says industrial agitator and mixer manufacturer Mixtec sales and projects manager Rudi Swanepoel.

The company, which has seven manufacturing plants worldwide, has specifically identified a great deal of opportunity in South and West Africa, where demand is dictated by new agitator applications as well as the replacement of old inefficient systems.

“Having completed numerous projects in South and West Africa, we see the need for innovations and improvements that will assist in shortening lead times and boosting productivity,” while also meeting the increasing need to cut costs and save on energy use, notes Swanepoel.

He says Mixtec’s ability to refurbish and improve on existing mixing systems has aided the mining industry by not only reducing power consumption but also increasing the operational life of existing agitators. The delivery of these outcomes is made possible by incorporating new impeller technology and the latest engineering capabilities for the manufacturing of agitator drives.

“Our agitators are employed throughout the world in mining and refining projects where we have used our advanced impeller designs to solve problems involving gold leaching, carbon in pulp adsorption, biological leaching, flotation, conditioning and attrition scrubbing.”

An Answer for Africa

Mixtec believes its mixers and agitators are appropriately matched to the African mining industry’s operating environment, where projects are remotely located, as its mixers are custom designed by its mixer design specialists.

Leveraging its globally based research and development departments and laboratories, the company can constantly test and improve on its products, as well as provide testwork for more demanding and uncommon applications at its clients’ request.

“Having our own on-site laboratory in South Africa also allows us to constantly develop and test new impellers, their power numbers and efficiency, enabling us to offer an ever-improving quality of service and more efficient designs. Our customer design service and fluid mixing laboratory is also capable of producing a complete mixer design even if little or no data is available, with the aid of computational fluid dynamics (CFD) guides, fluid handling facilities and experienced application engineers. With the ability to swiftly assemble small-scale versions of larger mixers in the field, we can quickly and accurately analyse problems and respond to these at a rate unmatched by our competitors,” highlights Swanepoel.

Seeking to expand Mixtec’s footprint in Africa in line with its global expansion strategy, the company is approaching new and existing mineral processing and refining plants which it believes would benefit from its designs and equipment.

The company has noted great development on the continent, owing to the progress of copper/cobalt mines, as well as opportunity surrounding gold tailings and recovery plants.

Mixtec has been involved in delivering projects at gold mines in Ghana, Senegal and Côte d’Ivoire, as well as a copper/cobalt mine in the Democratic Republic of Congo. It also supplied a phosphate mine in Morocco with pipeline phosphate slurry tank agitators manufactured in South Africa.

Factoring in all aspects of a design, namely the location, the need and the implications of the project, Swanepoel says it ensures that its designs exceed the desired outcome. The company focuses on the specific process considerations of the application, the mechanical integrity of the mixing components and the drive system integrity to ensure the most suitable solution for an application.

“We match the right impeller with your mixer by considering the profile, pumping and power needs of the application, while also factoring in the velocity gradient, superficial (in-tank) velocity, pumping rate, tank turnover rate, tank shape, liquid level variation, the position of impellers and the direction of pumping to ensure a successful solution.”

In most cases, Mixtec’s mixers consist of a motor and drive system, output coupling, mixer shaft, seals and various impeller assemblies. “Given the variety of applications and processes mixers and agitators can be used for, we have divided them into different series – open top tanks, closed top tanks that require sealing, large-scale industrial agitators, side entry mixers and in-line static mixers,” explains Swanepoel.

Tackling Challenges

Challenges presented when servicing the African mining sector are delays in mining permit approvals, inadequate budgets, outdated knowledge of mixing technologies and developments, and the impact of smaller companies entering the market with inadequate technologies that are incapable of developing mixers or delivering mixing functions that are up to standard.

While there is not much Mixtec can do to assist with stalled mining permit approvals, which could lead to the delayed development of mining projects, the company is able to offer clients with inadequate budgets alternative solutions, without compromising on quality.

Its on-site laboratory in South Africa, fluid handling facilities and research engineers allow the company to find the best design to meet specific needs. Mixtec’s mixer and agitator designs are currently influenced by the demand for an extended life span, and continuous maintenance and technology upgrades.

“We use extensive CFD to virtually assess mixer performance under various conditions to aid the development of improved impeller design,” adds Swanepoel.

In line with demand for continuous technology upgrades, Mixtec’s research and design teams constantly improve existing systems and develop new product offerings. Products and processes are regularly changing, and Mixtec sees value in being a part of the design process from the start so it can offer the best possible solution to any application.

To ensure the supply of fit-for-purpose technologies, Mixtec uses three-dimensional modelling software complete with finite element analysis when designing new products to ensure that all load factors are taken into consideration, providing the best possible life span.

Based on computerised simulations, a physical design is produced for trials in the company’s laboratory to enable its research and design engineers to perform the required testwork to verify the simulation’s results.

However, the replacement of inferior mixers and agitators supplied to existing plants in Africa by other companies has also been a source of revenue for the company, which finds that often the inferior mixers and agitators it replaces have been sourced from Chinese manufacturers.

The common causes of failure are usually the result of a poor design being specified for an application, as not all the requirements of the application have been considered. Often compounding the situation is the use of poor material and inferior fabrication quality.

“Dynamic systems such as mixers need to be maintained and manufactured to the best quality and standard, ensuring smooth operation. Incorporating stringent fabrication methods, we use the latest international standards in inspection procedures and machine tools to provide the tolerances for accurate alignment and a precision-made product.

“To reduce downtime and ensure mixers are operating efficiently, we further guarantee that the appropriate spares for these systems are available for installation immediately after mixers have been commissioned,” says Swanepoel.