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Spirals in Australian mineral processing
Mining is an important industry for Australia and contributes significantly to the country's economy. Minerals mined in Australia include iron ore, coal, gold, copper, nickel and zinc. Spiral concentrators are used in mineral processing for separating minerals. Multotec Australia has a range of gravity concentration equipment for effective mineral concentration. The range comprises end-to-end spiral solutions, from process audits and test work, to complete spiral concentration plants optimised for your specific process. With our global branch network, we support your spiral application with tailored field service and complete availability of spares for your plant.
What is gravity concentration?
Gravity concentration is a mineral processing technique used to separate minerals based on their specific gravity or density. This is a physical separation process that uses differences in mineral density to separate them.
It takes advantage of the fact that dense minerals settle faster than lighter minerals when placed in liquid or water. In this process, a slurry of crushed ore is placed in a vessel such as a shaker table, spiral concentrator, or jig designed to facilitate mineral separation based on density. The specific gravity of a mineral is the ratio of its density to that of water. For example, gold has a specific gravity of 19.3, which is 19.3 times denser than water. This high density facilitates separation from other minerals by gravity concentration techniques.
Gravity concentration is best for coarse particles as they settle faster than fine particles. Therefore, crushed ore is usually sieved to remove fine particles before being fed to the gravity thickener. Gravity concentration techniques can be broadly divided into two categories:
- High density media separation and gravity separation. Dense media separations involve the use of dense liquids such as: A magnetite or ferrosilicon suspension that produces a medium with a density intermediate between that of precious minerals and that of gangue. This allows valuable minerals to be separated from gangue based on differences in density.
- Gravity separation technology uses a device that creates a slurry of water and crushed ore that is placed on a vibrating table or spiral concentrator. The vibrating table consists of a slightly slanted flat surface, and as the slurry flows over the table, heavy minerals settle to the bottom and are collected, while lighter minerals are washed away. A spiral concentrator consists of a spiral chute used to separate minerals based on their specific gravity. The slurry is introduced at the top of the helix and as it flows down heavy minerals sink to the bottom of the helix and light minerals are carried to the outer edge of the helix.
Our range of spiral concentrators
Multotec Australia offers a wide range of spiral concentrators that can be found at our branches in Brisbane, Mackay, Perth, Newcastle, Newman and Emerald, Our range of spiral concentrators is designed for use in the mineral processing of chrome, coal, iron ore, gold, nickel and zinc. The video below gives guidance on how to choose the right spiral for your operation.
This spiral is suited for applications in coal processing, as it allows the near dense particles a longer retention time for improved separation efficiency. The denser particles are guided into the centre column after the first four turns (allowing for greater capacity in the spiral). The remaining clean coal and middlings are then subjected to repulping. After this process, the spiral turns three more times, one more step to remove what must be discarded. This is followed by another repulping stage before the final distribution of coal, which is caused by three more spins before it finally splits into clean coal, middlings and discard material.
Benefits & features of our SX 10 spiral concentrator
- The spiral is a primary & secondary stage on one centre column. The first off-take removes ash, opening up the available separation surface of the spiral & allowing the remaining material to separate more easily
- High capacity, low relative density cut
- Delivers increased separation efficiency and improved coal recoveries
- Reduced cut point of 1.55 g/cm3 results in cleaner coal with less waste being achieved in a single stage
The UX7 ultrafine spiral concentrator is a cost-effective recovery treatment for tailings dams material, tailings storage facilities, high-grade fine material, and ultrafine material. It has no moving parts and no chemical requirements, allowing for easy operation where operators can visually check spiral efficiency.
Benefits & features of our Ultrafine Spiral concentrator
- Achieve more tailings recovery – 100 μm & smaller
- Access value from previously discarded tailings
- Reduce loss of high-grade ore to tailings
- Ideal for solids concentration of 30 – 60%
- Ideal for solids tonnage range of 3 – 7 tons per hour
Multotec Australia supplies custom designed and optimised the single (SX4) and double (SX7 and MX7) coal spiral concentrators that are supplied with steel rubber-lined or PVC/polyurethane pipe launder systems. The spiral models each have different combinations and have been developed to suit the coal quality.
Features and benefits of Multotec’s Coal Spiral Concentrators
- Available in single, double or triple starts
- Up to 7 turn configurations
- Compact, modular design reduces floor space requirements
- Rubber integral edge prevents spillage
- Specialised Auto Reject Channel® on the MX7
- Construction material selected to provide long life and low cost
This range of spirals helps to separate fine heavy minerals. We offer a variety of these spirals to best suit your mineral processing requirements. View our range here.
Available in the HX3, HX5 and SC ranges, the modular frames house two spiral assemblies and have several optional features that can be fully dismantled for retrofitting purposes. Componentry includes the spiral trough, auxiliary or sliding splitters, launders, distributor and piping, feed box, and product box with product splitters. All components have salient features to provide longer life, increased production and ease of repair, as well as reduced downtime.
Features and benefits of Multotec’s Mineral Spiral Concentrators
- 3 product ranges – HX3, HX5 and SC
- Ideal for high, medium, or low-grade profiles
- Reduces plant footprint by more than 33%
- Construction material selected to provide long life, low cost and low maintenance.
HX and SC Mineral Spiral Concentrators
This range of spirals is an extension of the mineral concentrator range and is suitable for applications in chrome, irone ore, copper, gold and other high-density minerals. These spirals can allow for separation of fine heavy minerals in the size range of 1.5 mm to 0.04 mm.
Features and benefits of Multotec’s HX3 and HX5 Mineral Spirals
- 1 000 mm in diameter with 3 and 5 turn units
- Tonnage rating per start from 4.0 tons per hour – mineral type dependent
- Ideal for low grade ore where large tonnages are processed
- Plant footprint can be reduced by more than 33%
- Materials of construction provide long life, low cost and reduced maintenance
Multotec’s innovative spiral manufacturing process
Multotec’s gravity concentration design and manufacturing processes are consistently changing to keep up with both technological advances and attempts to improve our solutions. Our new process involves spraying and laminating polyurethane on the working surface of the spiral with fibres and other chemicals in order to give structural support and strength. Read more about how we have improved our process for your benefit.
Spiral concentrator maintenance
Watch a video demonstrating spiral plant testing
Multotec Australia offers end-to-end services across all its Australian branches for your gravity concentration plant. Our services include testing spiral equipment, field services, ongoing optimisation and any required maintenance. We also offer a range of spares and accessories for all our spirals.
Our gravity separation services include:
- Test work on spiral concentrators
- Consultation on spirals, processes and plants
- Commissioning of all spiral equipment
- Ongoing optimisation<
- Design assistance
Learn more about our field maintenance services here.
Multotec Australia offers a range of gravity concentration equipment for application in the mineral processing of some of Australia’s most valuable commodities including, irone ore, coal, gold, copper and nickel. Our range of spiral concentrators is designed and manufactured to ensure that the best possible results are obtained from the gravity separation process. We offer services and maintenance for all our spiral equipment. Our branches in Australia are located in Brisbane, Mackay, Perth, Newcastle, and Emerald, making it easy for you to achieve your mineral processing goals. Put us to the test
Frequently asked questions
What are the advantages of a spiral concentrator?
Spiral concentrators have several benefits, including affordability, prolonged equipment life, minimal space requirements, and effective fine material recovery. To assess whether the material is separating properly, they can also be examined visually.
What is a spiral concentrator?
A spiral concentrator is a contemporary, low-cost, high-capacity device. It was created for the slurry-based concentration of industrial minerals. It functions by combining the solid's hydrodynamic dragging characteristics and particle density.
What are the uses of spiral concentrators?
Spiral concentrators are used to process heavy mineral sand deposits, including monazite, zircon, ilmenite and rutile deposits. More recently, spiral concentrators have been widely used to recover fine coal as well as gold, iron ore and other minerals.
What are the disadvantages of spiral concentrators?
The disadvantages of spirals include relatively high specific gravity cut-points, relatively low unit throughput, the need for multi-stage processing, and limited acceptable feed size range.
What determines the performance of spiral concentrators?
The specific gravity and particle size of the minerals being processed, the water flow rate and pressure, as well as the shape and size of the spiral channel, can all have an impact on the effectiveness of spiral concentrators.
Why are spirals used in mineral processing?
Spiral concentrators are low-cost equipment, used in mineral processing to process heavy mineral sand deposits, usually containing minerals such as rutile zircon and monazite.
Our gravity separators for heavy mineral applications, including iron ore, chrome, mineral sands and other high density minerals, separate particles in the size range 2 to 0.04 mm.Multotec Australia has a range of spirals, from 3 to 12 turns, with high-, medium- and low-gradient profiles. Our high capacity spirals (the HX series) provide a per-start tonnage rating of 4 to 7.5 tons per hour, depending on the mineral type, and is especially suited for the treatment of low-grade ore, where large tonnages are processed.
Mineral spiral separator components include the spiral trough; sliding or auxiliary splitters; launders; distributor and piping; feed box; product box and stainless-steel product splitters; and the discharge chute at the bottom of the modular housing frame. Our spiral separators have a diameter of +/- 950 mm.
Our gravity separators for heavy mineral applications, including iron ore, chrome, mineral sands and other high density minerals, separate particles in the size range 2 to 0.04 mm.Multotec Australia has a range of spirals, from 3 to 12 turns, with high-, medium- and low-gradient profiles. Our high capacity spirals (the HX series) provide a per-start tonnage rating of 4 to 7.5 tons per hour, depending on the mineral type, and is especially suited for the treatment of low-grade ore, where large tonnages are processed.
Mineral spiral separator components include the spiral trough; sliding or auxiliary splitters; launders; distributor and piping; feed box; product box and stainless-steel product splitters; and the discharge chute at the bottom of the modular housing frame. Our spiral separators have a diameter of +/- 950 mm.