Large FLSmidth bolted thickeners for Mozambique plant
The installation, which includes E-Volute™ feedwell technology for superior flow distribution, will contribute to achieving optimal water balance in the customer’s coal plant in Mozambique.
Measuring 45 metres in diameter, the thickeners will assist in achieving a drier product from the filter plant and control the density of material to the belt filters. According to Howard Areington, FLSmidth’s General Manager for Capital Sales in Sub-Saharan Africa, this will improve the plant’s output.
An important aspect of a bolted thickener is that its construction is quicker and safer, he says, requiring only a fraction of the welding to be conducted on-site. This suits the conditions for the project, which is remotely located.
The extent of welding in the construction of normal steel thickeners typically runs into kilometres. It is far more cost effective to do this in controlled workshop conditions, where quality can also be better managed. By contrast, the amount of on-site welding required by a bolted thickener can be measured in metres.
As mentioned, the thickeners include E-Volute™ feedwell technology for superior flow distribution. This leads to lower flocculant consumption, better settling rates and improved overflow clarity for the optimal performance of the thickener.
“Controlling the cost of flocculant – the single most important reagent in this process – is key to our thickener design,” he says.
Despite the COVID-19 lockdown, good progress was made on the fabrication of the thickeners in South Africa, according to FLSmidth Project Manager Kevin Kockott. This has been managed by leveraging FLSmidth’s global resources and the design teams’ ability to work remotely.
The design of the thickeners features FLSmidth’s well proven bridge-mounted rake drive, known for its simplicity and ease of operation. The rake mechanism includes a proprietary low-profile style with tubular rake arms. These are able to move high-yield stress material with minimal drag and torque exerted on the drive mechanism.
Areington emphasises that all mechanical elements are designed for long life. This limits the intervention of the plant personnel to regular maintenance.
Most of the large thickeners operating in the southern African market – up to 120 metres in diameter – have been supplied by FLSmidth. He highlights FLSmidth’s impeccable group pedigree in terms of thickeners.
“Our large installed base of units around the world is testament to our cutting-edge thickener technology,” he says. “We have also secured most of the market for paste thickeners globally.”
FLSmidth’s involvement with the Mozambique project goes back almost a decade to the first phase of the plant’s development, according to Vice President Mining in Sub-Saharan Africa, Middle East and South Asia, Alistair McKay.
This article was first published in Mining Review Africa Issue 3, 2021