Ensure unparalleled product quality by using premium-grade filtration materials.
Markert - Advanced Textile Filter Cloths
For a century, our family business has stood for tradition and motivation to achieve maximum performance in our products. As specialists in textile filtration manufacturing, we thrive to serve our customers with customized products that are ideally suited to their operation’s respective application. Markert is one of the market leaders in textile filtration. We operate close to our customers with dedicated sales engineers.
Mining Filter Fabrics for Tailings & Concentrates
Filtration technology is crucial in the mining industry, playing a key role in the processing of ores and minerals. Concentrates and tailings, need effective dewatering to reduce moisture content and manage waste. Efficient filtration improves the quality of concentrates, lowers transportation costs, and minimizes environmental impact.
Advanced filtration equipment such as filter presses or vacuum filters in combination with textile filter cloths that are well matched to the process are essential for handling the high demands of mining operations. These systems enhance operational efficiency, reduce energy consumption, and support sustainable practices.
This white paper explores the importance of filtration in mining, highlighting key technologies and best practices that drive performance and sustainability in mineral processing.
Where is filtration heading in Mining?
Concentrates & Tailing in the mining industry
Mining involves several steps of filtration:
In mineral processing, liquid solid filtration mainly occurs in the dewatering/accumulation of concentrates and tailings.
The concentration process aims to separate valuable minerals from unwanted gangue materials (nonminerals). This process involves several methods depending on the type of mineral:
The output of these processes are concentrates, which contain a high percentage of the desired metal. These concentrates are sent for further processing or refining steps, such as smelting and refining.
Filter cloth requirements within the Mining Industry:
Particularly in mining applications, there are sharp particles in the suspension that can damage the filter cloth. Friction occurs during each cycle through the cake discharge and filling processes, which results in chafing of the cloth.
The extraction of gold in mining poses a special challenge to filtration due to the addition of chemicals. This process is widely known as Merrill-Crowe process and a used method for the recovery of gold and silver from cyanide solutions. The process involves removing precious metals from cyanide leach solutions through a series of steps, including filtration.
Leaching Process
The ore containing gold and silver is ground and mixed with a cyanide solution, which dissolves the precious metals. This creates a “pregnant” solution containing dissolved gold and silver.
The pregnant solution often contains fine suspended solids such as clay, silt, and other particulates. These solids must be removed, as they can interfere with the process and reduce efficiency.
Clarifiers like pressure leaf filters are used for this purpose. The pregnant solution is passed through clarifiers—typically large tanks where flocculants (chemicals that promote the clumping of fine particles) are added. This helps to settle out the suspended solids.
Clarifiers work through sedimentation, allowing the clear solution to overflow while the solids settle to the bottom. The clarified solution is then passed through filters (such as leaf filters) to remove any remaining fine particles, resulting in a clean, clarified solution.
4.1 Filtration requirements & solutions for clarification
Requirements for the filter bags:
Our Solution for Clarification: PPD 11293
Woven and reinforced with a high amount of heat resistant threads
Tailings are the leftover materials after extracting valuable minerals. They primarily consist of fine slurry, rock dust, chemicals, and residual minerals. Tailings are a byproduct that must be properly managed to minimize environmental and safety risks.
Key Aspects of Tailings Management:
5.1 Filtration requirements & solutions for tailings
Filter cloths in mining applications are exposed to extremely high mechanical load, causing abrasion mainly in feeding areas. Increasing the lifetime of filter cloths is important for reducing OPEX costs. Our filter cloths improve your production by offering a longer lifetime, perfect dewatering and cake separation. We also use a special rubber material to minimize abrasion in feeding areas, extending lifetime of our filter cloths significantly.
In addition to the selecting the perfect fabric, a perfect design and strategic reinforcements are decisive for the durability of the filter cloth. See the picture of a poor feed reinforcement (page 12). The feeding shoes made of rubber and metal tend to rub through the cloth material:
Customer: silver mine with 2x FFP 3512 with 100 Plates and cloths size: 2.420x3.982mm
Application: Silver Tailings, with a high content on flocculants, PSD 30-40μm and cycle time 15-16 min.
Issues: sticky cake, clogging
Cloths in use: Multifilament with 20cfm
Our Solution: NKD 11299 Nylon Monofilament with 60cfm
Conclusion: Provides lifespan of 8,290 cycles against the previous 4,000 cycles.
It also provides benefit for the filter press as less shaking of the cake is required.
Most frequent damages occur in the area of the feeding shoes.
! Under a sand blasting test, our production material OMS 557 has far exceeded expectations and demonstrated outstanding tenacity under the most extreme conditions.
! Black reinforcement called OMS 557 sewed on our sewing robot provides extreme protection from the feeding shoe.
General
7.1 Horizontal vacuum belt filters
Success Story: Phosphoric acid
Di-Hydrate Conditions:
Our Solution: DID 11137
7.2 Horizontal pan filters
Our Solution: PPD 3115 and PPD 90314
PPD 3115: our standard solution for hemi-hydrate
PPD 90314: premium grade solution for hemi-hydrate
Longer service life due to:
Greater thickness (+0.2mm)
Higher tensile strength (+1100 N/5cm)
Thicker yarns (+0.1mm in warp and weft)
Heat resistant PP yarns
7.3 Rotary drum filters
Success Story: Copper Concentrates
Our Solution: PPPD 3146
Double layer fabric
No need of drainage fabric/backing cloth
Better residual moisture possible
Higher throughput
Belt width up to 8m x 25m
7.4 Disc filters
General
Disc filters are continuously operating pressure filters.
They can be described as a combination of a drum and plan filter
Filter segments/bags are placed horizontally
Filtration principle as for the drum filter
Emptying:
Mechanically via scraper
Via pressure surge
Reasons for fabric failure
Mechanical stress at cake discharge
Pressure shocks can cause the welding to tear
Mechanical scrapers rip the fabric open
Insufficient filtration performance
Success Story: Ferrutex® elastic filter bags
Elastic stretch Nylon bags (multifilament)
“Self cleaning” bag
High capacity all the time
Durable = long life
Clear filtrate
Dry cake
7.5 Disc filter steel sectors
A newly designed steel sector with the following benefits:
Very light segment weight of only 18 kg instead 28kg
Fast and easy segment change due to the special bayonet shape of the segment foot (just one operator)
Optimized hydraulics ensure fast filtrate drainage and efficient compressed air blow-back for cake discharge
No need for a backing cloth
Shape of segments helps to seal the filter bag and prevents product loss
special groove and no need to use screws anymore
Sectors are compatible with the following vacuum disc filter OEM’s:
Bokela
Eimco
FLSmidth
Dorr Oliver
Gaudfrin
Andritz
Krauss Maffei
Development process for a custom engineered filter fabric
Labratory Testing
Markert runs a laboratory analysis of the filter cloth with subsequent analysis of the results. This includes determination of: