Multotec’s modular spiral test plants – a quick route to production

As seen in Modern Mining April 2021.

Building a new processing plant is capital and time intensive. With a small capital outlay required, coupled with short lead times, Multotec’s modular spiral test units enable start-up operations/junior or artisanal miners to start small and ramp up as they generate cash flow.

By Munesu Shoko. 

In a world where access to funding remains the single biggest hurdle for junior miners and capital dilemmas are at the forefront of junior mining executives’ minds, Multotec’s modular spiral test plants offer a quick route to production. 

Christina Ramotsabi, GM gravity concentration at Multotec, says building a new plant is generally a capital and time intensive exercise, but with Multotec’s modular plants, customers can start small and ramp up as they generate cash flow. 

Multotec offers spiral test units for both heavy minerals and coal applications. Heavy minerals plants, explains Ramotsabi, comprise four stages of spirals and are capable of processing up to 20 tonnes (t) of dry solids per hour in the feed to the spirals. The coal test plants comprise double-stage MX7 and SX7 spirals, and are capable of processing up to 40 t of coal per hour to the spirals. 

Cost-effective solution

A key benefit of these modular solutions is the lower capital outlay compared with big plants. “In terms of price we are looking at anything up to R5-million for a fully installed four stage spiral plant. From a capital expenditure perspective, this is cost-effective for junior or artisanal miners. They can start small and scale up as they generate enough cash flow,” she says. 

Given the compact and modular nature of these plants, lead times are anything between eight and 10 weeks, giving customers a quick route to production. Because of their modular nature, these plants can be erected in a day or two after being delivered to site. The plants have been designed to stand on a level concrete pad or compacted surface, eliminating the need for costly civils on site. 

“The plants come pre-assembled in three main sections, making them easy to transport and erect. They can be easily moved from one site to the other and be re-erected in a short space of time,” explains Ramotsabi. “Pre-assembly means that there isn’t much work to be done when the plant arrives on site. In a day or two the plant can be erected and start operating. From a transport perspective, the plant comes in three main sections, meaning that it can be transported on three flatbed trucks.” 

Benefits abound

Multotec’s modular spiral test units are designed to be self-standing. They have a ‘plug and play’ capability and come complete with all the complementary equipment. For example, the heavy mineral plant comes complete with desliming and dewatering cyclones, pumps and tanks, while concentrate and tailings stacker cyclones are optional. A four-stage spiral circuit – Rougher, Cleaner, Re-Cleaner and Scavenger – is used and spirals are interchangeable depending on the mineral being treated. 

“The coal modular plant – designed to handle a 40 tph feed – comes complete with a sieve bend, desliming cyclones, pumps, tanks and spirals,” says Ramotsabi. 

Flexibility is a key attribute of these plants. Versatility allows for the flow sheet to be adapted to suit specific applications. The heavy mineral plant can be deployed across commodities, including chrome, copper, tin and mineral sands, among others. 

“The heavy mineral plant can also process both run of mine (ROM) material and tailing dumps. We have designed the plant to be flexible such that the spirals are interchangeable and can be utilised across a variety of minerals,” explains Ramotsabi. 

When in transit, the test unit’s stability is maintained through support braces and dedicated lock-out switches for each pump. 

From a design perspective, the original plants had cat ladders, which were considered to pose safety hazards for operators. The new generation plants have been redesigned to include external walkways, making it safer for operators to do process control and access the different levels of the plant with ease. 

Meanwhile, Multotec, through its field service team, provides installation and commissioning assistance. Aftersales support is provided throughout the lifecycle of the plant by the company’s application engineers. The company also provides a consultation service, while test work on spiral concentrators is conducted at Multotec’s R&D facility or at plant sites. 

Increased uptake 

Given the array of benefits offered by these modular plants, Multotec reports an increased uptake in the market. To provide context, Ramotsabi says the company has in the past delivered 20 plants to a single customer processing alluvial chrome in different regions of Zimbabwe. The company also recently delivered two heavy mineral modular plants in Zambia, where they have been deployed in a copper application. 

“We also have a large installed base of these plants in South Africa. We recently sold four units in the Burgersfort area, where we now have around 7 plants in total operating in the area. We have 3 units in the Rustenburg area, and 5 in Mpumalanga area. Generally there has been an increased uptake of these plants in recent years,” says Ramotsabi. 
The biggest demand locally, says Ramotsabi, is in chrome applications. Responding to the industry’s need to re-treat chrome dumps, Multotec has in recent years adapted its versatile heavy mineral test plants to process ultra-fine chrome. 

“The majority of plants operating in South Africa are also in chrome applications. We have, however, also seen an increased number of enquiries from the mineral sands sector across southern Africa. Even locally in South Africa we have tendered on a number of projects in mineral sands,” concludes Ramotsabi. 
 

Key benefits of Multotec’s modular spiral test plants 
•    The spiral test units are stand-alone units and can be skid mounted
•    Easily erected on site, with three primary modules
•    The flow sheet may be adapted to suit specific applications
•    ‘Plug and play’ capability
•    Units are easily moved and re-erected
•    Optional extras on the plant include samplers and process flow meters