Dickinson group retrofits largest modular precast refractory components

The South African furnace and industrial services company, Dickinson Group recently retrofitted the largest modular precast refractory components ever manufactured in South Africa for heavy mineral miner Tronox Namakwa Sands’ open pit mine.

The Dickinson Group have retrofitted a 30t brick-lined iron ladle with a modular precast refractory lined ladle for heavy minerals miner Tronox Namakwa Sands’ mineral sands openpit mine and concentration plants in Brand-se-Baai.

Dickinson Group CEO Trevor Dickinson told Engineering News that the sizes of the precast modular blocks for the ladles were between 1.2 t and 1.6t each.

He explained that andalusite,which is a naturally occurring alumina silicate used mainly in the manufacturing of refractory products in the form of shapes, castings and monolithics,was used for the precast components.

Additionally, Dickinson pointed out that the company has invested R8-million in its precast division facility in Vereeniging, Gauteng, to improve the quality and range of its products.

He says the facility has enabled the company to manufacture precast components that are considerably larger than the previous products it produced.

“We are increasing production capacity at the plant, owing to the increasing demand for precast products by industry.”

Dickinson says in 2011 the company was contemplating closing down its precast division, which wasestablished in 1986, as it was becoming “increasingly unprofitable”.

However, in early 2012, Dickinson Group established a partnership with US-based Allied Mineral Products that specialises in manufacturing monolithic refractories.

Upgrading its precast facility has enabled DickinsonGroup to manufacture much larger precast components

“Allied is a global leader in the industry with manufacturing plants in the US, the Netherlands, India, China, Brazil and South Africa,” highlighted Dickinson.

In December 2012, Allied invited Dickinson Group to visit its manufacturing plants and associate company American Precast Refractories facility, in Ohio.

“We were impressed with what we saw and decided to invest R8-million in upgrading our precast facility instead of closing the precast division,” Dickinson enthused, adding that the precast division has since not only become a profitable part of the group’s operations but the facility will also be expanded from 500m2 to 1 500m2 by the end of this year.

Meanwhile, Dickinson Group Precast Divisional Manager Willie Nicklin explained that precast refractory shapes are not mass produced, but purpose-made products for a specific application, and that precast components are easy to install.

And Dickinson Group Business Development Manager Wayne Law pointed out that one precast block replaces about 30 bricks.

“An iron ladle, for example, can require as many as 3 000 bricks to build; however, only eight precast blocks are required to build the ladle,” revealedNicklin.

“Dickinson Group has also established an alliance with Canadian coke oven solutions provider VanocurRefractories for the manufacture of the company’s big block solutions for coke ovens. The big block solution provides the benefit of significantly reducing the number of joints on the coke oven walls as 150 modules of the big blocks replaces more than 4 000 normal silica bricks.”

He further noted that there are, therefore, fewer joints on the furnace, which reduces the number of potential failure points.

Additionally, Nicklin stated that a brick-lined ladle can take between four to six days to build, but Dickinson Group can build a ladle in just four hours using precast technology.

“Therefore, it significantly reduces downtime at an operation,” Law added.

Further, Nicklin divulgedthat using precast shapes for the furnaces has changed the nature of the operation from a bricklaying activity to a rigging operation, which is a “lesser-skilled activity”.

Law also pointed out that the company has replaced wooden moulds with polystyrene ones, which are easier to shape and fully recyclable.

“The company bought several new computer numerically controlled lathes, which cut polystyrene moulds to a recurring accuracy of 0.3 mm,” he said.

Moreover, Dickinson says historically precast components were manufactured using pan mixers, which mixes the refractory castable, without any significant intensity.

“However, we have bought several high-intensity mixers, which reduces mixing times from between 18 to 25 minutes to just eight to ten minutes.”

He says the high-intensity mixers ensure a more homogenous mixing solution, which results in stronger components being produced.

The new mixers have programmable water-dosage systems, which removes the need for water to be manually added to the mixing solution.

The company also bought new dryers, with programmable temperature control units, which eliminates manual temperature monitoring.

Precast components significantly reduce emissions that escape the furnace linings, owing to the tightly compounded nature of the components.

Dickinson said, with growing pressure from governments for industrial operators to reduce their carbon dioxide (CO2) emissions levels, precast components will become more popular because they can effectively contain CO2 emissions in industrial furnaces.

“This will greatly assist companies that operate large coking ovens, which are large CO2 emitters, to reduce their negative impact on the environment,” stated Dickinson.

He pointed out that merchant producer of high-performance foundry coke Erie Coke Corporation, in Pennsylvania, in the US, was also at risk of being closed down by the US government, owing to the high emissions levels of its facility.

“However, in the last five years, the Pennsylvania facility has become a model for clean operations because using precast technologies have significantly reduced carbon emissions,” said Dickinson.

He expressed belief that using precast shapes components at local operations, such as steel producer ArcelorMittal

South Africa’s coking ovens, will greatly assist in reducing the CO2 pro-duced at the facilities.

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