The machine, which can harvest 600 tons of unprocessed salt per hour, is the first of its kind to be built in Africa and has attracted European interest.
Port Elizabeth (Gqeberha), Eastern Cape-based ROVD Engineering have manufactured a large salt harvesting machine that is capable of harvesting 600 tons of unprocessed salt per hour. The machine has been manufactured for Botswana client Botswana Ash, which is a joint venture company formed between the Botswana government and private investors.
ROVD Engineering is an end-to-end industrial automation company, specialising in the design and manufacture of engineering solutions. Established in 1964 as a small general engineering company, ROVD is now a company that provides turnkey industrial automation solutions and systems to customers globally. These systems are designed, manufactured and installed to meet the customer’s specific requirements. Large CNC machining, fabrication, assembly and test are key focus areas within the company besides design and development.
The latest ROVD Engineering salt harvester, which was unveiled at the company’s factory in October last year, took nine months to build before it was commissioned by the client
The systems include, but are not limited to, cutting-edge material handling conveyor systems, trusted by global automotive manufacturers, and high-quality materials handling equipment used in the salt mining industry. ROVD Engineering is a subsidiary within the ROVD Group, which has four subsidiaries, with three situated in South Africa and one in the USA.
The latest ROVD Engineering salt harvester, which was unveiled at the company’s factory in October last year, took nine months to build before it was commissioned by the client.
The machine weighs just under 50 tons, has a 450kW motor and tank treads to get it moving at the harvesting speed of 5km an hour. The project cost for the new machine was approximately R18.5 million.
Other features of the machine are that the operator cab is fully enclosed and tinted to protect against the white glare, air conditioning and LED lighting for 24-hour operation, a 3G up-link to maintenance and production personnel and an advanced touchscreen control system
Salt production
The solar evaporation method is the oldest method of salt production. It has been used since salt crystals were first noticed in trapped pools of sea water. Its use is practical only in warm climates where the evaporation rate exceeds the precipitation rate, either annually or for extended periods, and ideally, where there are steady prevailing winds. Solar salt production is, typically, the capturing of salt water in shallow ponds where the sun evaporates most of the water. The water is moved through a number of ponds, slowly evaporating water to create brine solutions. The concentrated brine precipitates the salt which is then gathered by mechanical harvesting machines. This production method produces high-quality, high-purity salt, ranging between 99.6% and 100% purity.
In many instances harvesting of salt is still done by hand and it has been harvested this way since at least the seventh century, when Benedictine monks dug the canals of France that bring seawater into this marshland.
Salt usage also went through a tough period with the introduction of refrigeration and this became the preferred method of preservation.
But like all industrial advancements new uses for salt have been found.
The client Botswana Ash has an annual capacity of 300 000 tons of soda ash and has an annual capacity of 650 000 tons for salt. This is not the first machine that Botswana Ash has purchased from ROVD Engineering
“Our client Botswana Ash, which has an annual capacity of 300 000 tons of soda ash and has an annual capacity of 650 000 tons for salt. Salt is a complementary product resulting from the production of soda ash. However, salt has over 14 000 domestic and industrial applications,” explained ROVD Engineering MD Kenneth Richardson.
“In Botswana Ash’s case one of their main clients is Sasol Polymers, which is part of the Sasol Group of Companies. The chemical grade salt accounts for about 50% of the company’s sales of course grade, which is primarily used for the manufacture of Poly Vinyl Chloride, which is an input in the production of chlorine and caustic soda,” added Richardson.
Driving the project was home-grown ROVD Engineering’s head engineer Heinrich Gerber, who grew up in nearby Despatch, attended a local technical high school, then went to Nelson Mandela Metropolitan University to study mechatronics, a subject that combines electrical and mechanical engineering.
He led a team of about 100 people from ROVD Engineering, designing and building the salt harvester that is the first of its kind to be built in Africa and has also attracted interest from Europe. The company is the only plant in Africa to build such harvesters. The machine is powered by diesel engines that can cope with high altitude and the high temperatures typical of salt pans.
100 people from ROVD Engineering were involved in designing and building the salt harvester that is the first of its kind to be built in Africa. It has also attracted interest from Europe. The company is the only plant in Africa to build such harvesters. The machine is powered by diesel engines that can cope with high altitude and the high temperatures typical of salt pans
Other features of the machine are that the operator cab is fully enclosed and tinted to protect against the white glare, air conditioning and LED lighting for 24-hour operation, a 3G up-link to maintenance and production personnel and an advanced touchscreen control system.
The harvester will be able to provide updates to the engineers back at ROVD Engineering to ensure optimal use and maintenance and provide crucial data for future projects.
The ROVD Engineering took a conventional salt harvester into the 21st century, with a swivel cab that allows the driver-operator to keep an eye on the elevator putting salt into the trucks. Remote technology involved with the harvester can foresee any problems before they even occur, to save the client time and money.
Work began on the new harvester in September 2021 and Gerber was given the project because of his engineering background. It is the company’s 23rd salt harvester, designed to Botswana Soda Ash’s specifications and is an updated version.
ROVD Engineering has its own 650m² machine shop where manufacture, fabrication, assembly and test operations take place
Gerber was disappointed that he “couldn’t really give it a go” in the limited space of the firm’s assembly hall, but has set his sights on putting the machine back together in Botswana.
“The salt pans are flat as far as the eye can see with beautiful pods of flamingos in the distance. I keep imagining how cool it will be to be the one commissioning ‘my baby’.”
The harvester is not Gerber’s only “baby”. He has worked at ROVD for eight years and been involved in projects from mechanical design to electrical design, to software development and project management. Among the projects that stand out are a double-dump press that compresses wool into units for easy shipping, a new facility to control the flow of raw paper into a money-printing machine, and a lot of work for BMW, Daimler, Toyota, Nissan and VW.
Components machined in the company’s machine shop
ROVD group CEO Garth de Villiers says the harvester project was a complex combination of electrical, hydraulic and mechanical engineering. Soon it will be put into action to “pass the salt”.
“It is a great honour to see it finally completed,” said the chief buyer at Botswana Ash, Baboloki Kethlogetswe.
“The company has a wide reach in the SADC region, with clients in SA, Zimbabwe and as far as the Democratic Republic of the Congo. This is the backbone of our production, it is how we crush our salt,” said Kethlogetswe.
Lithium works well in computers, smartphones and electric vehicles
ROVD Engineering is expecting a boom in the industry as the world shifts to green energy and the use of lithium batteries in computers, smartphones and electric vehicles. Lithium is one of the salts that can be extracted as a by-product of salt mining.
ROVD Engineering is part of the ROVD Group. More components shown
The price of lithium, which is found in concentrations of mineral salt, has surged recently with the increase in battery-powered electrical cars. Lithium is also mined from ore but mineral salt concentration mining is on the rise.
Lithium is the lightest metal in the periodic table, and it’s used in all kinds of things. It makes glass and ceramics stronger. It’s a handy component in car parts and vehicle greases since it holds up well in extreme temperatures. It’s a mood stabiliser that helps treat bipolar depression. It also helped create the hydrogen bomb. It’s in pool chemicals, air scrubbers, polymers and refrigerants.
As consumer electronics have become more widespread manufacturers have realised that lithium is an especially useful ingredient for making batteries used in computers, smartphones and electric vehicles.
Roll work done in the ROVD Engineering machine shop
Lithium-ion batteries are now prolific in computers and smartphones. But in recent years, one product, in particular, is driving a surge in demand for the mineral: Electric vehicles. In 2015, batteries eclipsed glass and ceramics as the dominant end-use of lithium, and that use continues to mushroom.
So ROVD Engineering’s machine can deliver more than just salt on the table. The company says there is interest from Europe for the base of the salt harvester to be converted into exploration drilling rigs. And the potential for the machine to be used internationally so that companies can harvest the mineral salt concentration looks very encouraging.
For further details contact ROVD Engineering on TEL: 041 453 2530 or visit www.rovdgroup.com
