Tag Archives: Johannesburg

Tronox boosts mineral sands dredging process with help of IPR-supplied SlurrySucker

Following a successful one-week trial, heavy minerals company Tronox Mineral Sands has taken delivery of a SlurrySucker dredging unit from Integrated Pump Rental.

The SlurrySucker will remove sand from the process dams near the Tronox mining operation on South Africa’s West Coast. This installation enhances the safety and efficiency of the dredging process, which previously had to be carried out manually by a team of underwater divers, IPR said.

“The pumping capacity of the dredging unit will ensure optimal operation of Tronox’s dams which need to be kept at the required storage volumes at all times,” Ruaan Venter, Rental Development Manager at Integrated Pump Rental, said.

The dredging unit will assist Tronox in regularly cleaning sediment from its process dams, reducing the risk of pump blockage or failure. This solution aims to provide rapid results on a cost-effective basis, while the remote operation raises safety levels, the company added.

To withstand the corrosive effects of salt water, the SlurrySucker has been equipped with a stainless steel casing as well as stainless steel components including wear plates and impellers. The units were manufactured at Integrated Pump Rental’s facility in Jet Park, Johannesburg, South Africa.

The SlurrySucker dredging unit comprises a floating barge with an electric hoist operated from the side of the dam. This ensures a high level of safety with the barge being operated remotely, including the lifting and lowering of the pump. At Tronox, the SlurrySucker is designed to pump 150 cu.m/h of sediment – with a solids content of 50% – back to the thickener in the plant.

“The electrically-driven unit also makes sure that there is no risk of contaminating the water in the dams with diesel or oil leakage,” Venter says. The compact unit is easy to transport between the dams requiring dredging, making for optimal usage of the equipment.

With its local manufacturing capability and technical support offering, Integrated Pump Rental says it is well equipped to maintain the SlurrySucker out of its Johannesburg facility.

Multotec liners scrub up nicely for Morocco phosphate mine

In one of its largest scrubber installations to date, Multotec Rubber is helping a phosphate mine in Morocco achieve new levels of efficiency thanks to the installation of customised liners.

The scrubbers measure 6.5 m in diameter and 11 m in length – large dimensions necessitated by the process plant throughput of 12 Mt/y. The installation, conducted during the March quarter of 2019, was carried out in response to a serious challenge faced by the customer. The existing head plates were wearing out at double the rate of the shell plates. This was leading to additional maintenance shutdowns during the life of the liners, with associated extra costs.

According to Mohamed Trabelsi, Senior Sales Engineer at Multotec Rubber, the collaboration with the customer included sending a Multotec team to site to first assess the situation. Multotec already had a longstanding relationship with the customer at this process plant, with Multotec trommel screens having operated successfully at the plant for over three years.

“Our team of engineers were on site to gather vital operating information including throughput tonnages, particle size, charge levels and rotational speed,” Trabelsi said. “We also assessed the variable speed drive system.”

This data was processed using the Rocky DEM simulation software, in which Multotec Rubber has made a significant investment. Leveraged by engineers, this software can simulate the full lifecycle of liners and predict when the scrubber will no longer perform efficiently, according to the company.

Rocky DEM allows engineers to accurately simulate all operating parameters in the scrubber. These include the shape and size of ore particles in the slurry being fed into the scrubber slurry, the charge level, the linings, attrition rates, particle trajectories and the scrubber’s rotational speed, Multotec Rubber says.

“We can therefore simulate the actual operating conditions of the scrubber, as well as the performance of the head and shell liners,” Trabelsi said. “Upon our assessment of the results, it was found we needed a different configuration of liners to the previous one in this application. In fact, the solution was a uniquely designed liner configuration – quite different to what is traditionally used.”

He notes that, in Multotec’s experience of high throughput scrubber applications, it is critical to lift the material away from the head plate, thereby alleviating the sliding abrasion which causes excessive wear.

“Our objective was to ensure optimum wear life with the lowest total operating costs,” Trabelsi said. “Efficiency was enhanced by ensuring that the liner profile configuration was suited to the specific operating conditions. By doing this, the wear life in this application has been improved.”

Since installation, the liners have been performing in line with the customer’s expectations and are expected to have a lifespan of over five years. These lifecycle predictions also allowed the payback period to be accurately determined, assisting the customer in making the best operational and financial decision, the company said.

The liners are locally manufactured at Multotec Rubber’s ISO 9001:2015 facility near Johannesburg, South Africa, which has benefitted from continued investment in technology over the years, the company said.

“Our quality manufacturing facility expedites the production of liners engineered for individual applications,” Trabelsi said. “The entire process from design stage to installation took just 12 weeks – in response to the urgency resulting from the premature failure of the previous scrubber lining installation.”

Trabelsi also noted that – even after finding an appropriate solution – mines must constantly anticipate changing conditions in their process plants.

“As mines develop, the orebody changes; this brings changes to their throughput capacities and mill operating parameters,” he said. “If a process plant has liners that have run for 10 years, it is not necessarily a given that this liner configuration is still suitable for the application.”

He emphasises that it is critical to conduct an assessment exercise in every application, before quoting on a replacement liner. Most importantly, the liners should be engineered in accordance with the current operational parameters of the mine.

“This is why Multotec Rubber considers it so important that our engineers go to site and assess the actual mill operating data for themselves,” he said. “This makes it possible for us to gain access to the information from the plant operating system, so that the best solution can be engineered for the mine.”

Correctly designed liners will offer greater energy efficiency and reduce media consumption, according to Trabelsi. This is significant, as energy input and media consumption account for around 80% of the grinding costs in the plant – depending on the application.

“The more we are able to simulate, the more accurate information becomes available,” Trabelsi said. “We are then able to accurately predict the savings and payback period that could be expected at the plant – as a result of improved efficiency and reduced power consumption per tonne.”

ERP system ups inventor accuracy at Weir Minerals Africa’s Kitwe facility

Weir Minerals Africa’s newly upgraded Kitwe facility in Zambia, its hub for central and east Africa, is benefiting from the use of an enterprise resource planning (ERP) system that has seen inventory accuracy rates rise, according to the company’s Luhann Holtzhausen.

The branch officially opened in early 2018 and boasts a state-of-the-art logistics and supply chain management systems to match those at Weir Minerals Africa’s main distribution hub in Alrode, near Johannesburg, it said.

Luhann Holtzhausen, Weir Minerals Africa Supply Chain Director, said: “Our Kitwe branch now has a 100% location-controlled warehouse that runs off our ERP system with Wi-Fi-enabled scanners in place. This has resulted in the achievement of inventory accuracy rates in the high 90s.

Holtzhausen continued: “The technology and technical capacity in this facility enables us to pick and bin items in real time. This will match any other system that customers may have seen globally and is also a benchmark within Zambia.”

The new warehouse is all under one roof, with high visibility through natural and artificial lighting, where every product is clearly labelled with bin location and barcodes for easy tracking, Weir said. Shelving of up to three metres high keeps all items neatly stacked, easy to identify and quick to retrieve.

“The right goods in the right quantity in the right place means that when a customer asks for an item, we know that we have it and can find it without delays,” Holtzhausen said.

As part of the company’s operation-wide system, the stockholding of the Kitwe warehouse can be viewed in real time by the supply chain management team in Johannesburg. Holtzhausen emphasised the importance of the ERP system’s ability to track trends in customer usage in a systematic and methodical manner, to avoid any stock-outs on mine sites.

Lack of timeous access to spare parts and equipment can be costly in terms of operational downtime, particularly at remote mines that take time to reach, Weir said.

“In addition to the high accuracy of our data on warehouse inventory, our systems also give us end-to-end velocity measurement to monitor the flow of goods from receipt at our warehouses to the actual time of delivery at the customer’s location,” Holtzhausen said.

Weir Minerals Africa has 75 stocking locations across the southern and central African region, and ships nearly 100,000 items each year from its main distribution hub in Alrode.

ANDRITZ pumps draining flooded mining tunnels in South Africa

Just as IM’s water management feature goes live, ANDRITZ has released details of a project it has been working on to de-water old mines in Johannesburg, South Africa.

South Africa has been dealing with an acid water problem in recent years. Underneath the old gold mining city of Johannesburg is a lake containing heavily contaminated water, which spreads horizontally and vertically into the abandoned pits of the former gold mines, according to ANDRITZ.

The water line has reached a critically high level, as determined by the specialists from the ANDRITZ subsidiary, ANDRITZ Ritz, in Schwaebisch Gmuend, Germany, which was given the first order to drain the mine water back in 2010.

The execution of the project was delayed by four years, however, and it was only in Spring 2014 that two powerful ANDRITZ submersible motor pumps were installed in the middle of Johannesburg city centre, in the so-called ‘Central Basin’. Each pump is capable of bringing 1,500 m³/h (1.5 million litres per hour) of water to the surface, according to ANDRITZ; with 60 million litres of water per day pump, it is a never-ending task, ANDRITZ said.

“In Johannesburg, however, acid mine water is an ongoing problem. Rainwater seeps into the tunnels and reacts chemically with residual minerals like pyrite, producing corrosive sulphuric acids. In the worst case scenario, this can result in a pH value of 2, which is enough to cause lasting damage to humans and the environment.

“Because of this corrosive acid, the Johannesburg pumps had to be completely redesigned. The design is based on ANDRITZ’s proven HDM (Heavy Duty Mining) technology, which uses the concept of a double-suction pump. The thrusts produced are offset by the counter-rotating arrangement of the impellers and the pumps run without axial thrust, giving a properly maintained pump a service life of 10 to 15 years.”

The pumps for the Johannesburg project are a tailor-made, customised design built for this special individual application, according to ANDRITZ. Part of the new system is an encapsulation of the submersible motors (see top photo), which enables the creation of an internal pressure higher than the external pressure. This prevents the intrusion of the corrosive water and the components inside the motor being attacked and possibly destroyed. “At the same time, the water being drained is used to cool the motor by means of a heat exchanger,” ANDRITZ said.

ANDRITZ engineers spent weeks developing the sophisticated technology needed to encapsulate the motor so it could withstand the higher internal pressure. The first two pumps have been running since June 2014. These 21-t pumps, each 15 m long with a 1-m diameter, were installed side by side in March, 5 m apart, but could only be started after completion of the water treatment plant.

Freely suspended on 430-m-long duplex steel pipes, they transport the acid mine water to the surface and onwards into an adjacent treatment plant (pictured). Here, through the addition of lime, the pH value is raised, the acid is neutralised and the heavy metals dissolved in the water are absorbed and precipitated as hydroxides, ANDRITZ said.

The South African authorities are planning a total of three pumping stations, which will each be developed at the mines’ disused extraction shafts. In addition to the Central Basin in Johannesburg’s city centre, invitations to tender for the ‘Eastern Basin’ and the ‘Western Basin’ are currently in progress, according to ANDRITZ.

“The long-term goal is to force the water level in the flooded mines back from its current level of approximately 200 m to a depth of 1,000 m, and to keep it there, to then be able to begin mining gold and gold ore in the drained upper layers of the mines once again,” the company said.

Weir Minerals Africa’s supply chain efforts providing miner payback

Weir Minerals Africa has been upgrading its supply chain system over the past four years and the company says its mining customers are feeling the positive effects.

According to Weir Minerals Africa’s supply chain director Luhann Holtzhausen, the company ships almost 800,000 bespoke items each year from its main distribution hub in Alrode, near Johannesburg, South Africa.

Leveraging both modern technology and an innovative management approach, it has raised its warehouse stock accuracies to 98% over the past four years, above the global benchmark of around 95%, the company said.

Holtzhausen said: “Our streamlined supply chain management ensures 70% of our products and components are delivered within two weeks of a sales order being received. Our inventory accuracy has also raised the on-time delivery performance over the last year above 90%.”

Between 3,000 and 5,000 parts are shipped each day from the Weir Minerals Africa Alrode facility. These volumes have grown 20% year-on-year since 2016, which the new systems can still comfortably manage in a single-shift operation, according to the company.

Eleven to 14 super-link trucks, which range in capacity up to 30 t, leave the facility each week to destinations in southern and central Africa. In addition, there are two to four container loads shipped to other destinations by sea.

Holtzhausen said: “Our new systems and processes provide management with real-time visibility of demand and stock in all offices across Weir Minerals Africa’s 75 stocking locations. This also gives us end-to-end velocity measurement to monitor the flow of goods from receipt at our warehouse to the actual time of delivery at the customer’s location.”

The same systems are installed at the company’s newly upgraded Kitwe distribution facility in Zambia, streamlining its capacity as a strategic distribution hub for central and east Africa, Weir said.

The benefits for customers of these improvements in supply chain efficiency include reduced lead times and less possibility of stock-outs on customer’s sites, the company said. “This, in turn, gives mines improved availability of equipment, less downtime and higher productivity.”

Holtzhausen concluded: “A significant advantage of optimal supply chain management is that customers gain confidence in our ability to deliver. This means that they can start holding less stock themselves and free up substantial amounts of their working capital.”