2019 Archive : The Use of Geotextile Tube for Copper Slurry Dewatering

Project Details

Fabric 1

ACETube®
Producer: ACE Geosynthetics Inc.
Supplier: ACE Geosynthetics Inc.

Please describe the project specifications

The project is located in a copper mine in Chile. During the process of beneficiation of the copper ore, due to the large amount of water washing out the residual tailing pond, it is necessary to empty the limited storage space in order to allow more capacity for treatment.
Therefore, ACETube® geotextile tubes are applied in the dewatering treatment of the tailing sludge. After dewatering, the liquid can be recycled and used in the mining area where the water supply resources are scarce. The sludge cake is entrained with precious metals and can be resold, so the fine content in the sludge is required to be retained as much as possible.
A. Features of this project
1. Copper tailings sludge, total 40,000 m3
2. The sludge moisture content is about 80%, and because of the large amount of heavy metals entrained, the unit weight of the sludge is as high as 30 kN/m3, and the unit weight of the sludge cake after dewatering is 32 kN/m3
3. In order to prevent the filtrate from penetrating into the formation, geomembrane is laid under the geotextile tube to block the leakage. In addition, the drainage channel is excavated around the ACETube® sludge dewatering area to collect the filtrate and recycle it.

B. Features of the ACETube® applied in this project
1. Material: high tensile strength geotextile fabricated by PP multifilament
2. The fabric structure is specially designed to meet the owner's request to retain a large amount of fine aggregates without affecting the dewatering efficiency;
3. Circumference of around 17.2 m, lengths of 24 m to 30 m.

What was the purpose of this project? What did the client request?

The mine originally used a filter-type dewatering machine, but the maintenance cost is high. Therefore, the owner wants to find another method with low cost and reasonable processing time to empty the tailings pond, so that a large amount of filtrate can be retained and reused in the mining area. However, the workable area is quite limited.

Therefore, the owner expects a good value method which is better than the original dewatering with a filter dewatering machine, at the same time meeting the above requirements.

What is unique or complex about the project?

1. The sludge contains heavy metals, and the unit weight is high, causing the geotextile tube having to withstand large tension.
2. ACETex® geotextiles are specially designed to provide high water permeability in very small openings, which meets the arduous challenges of the owner's requirement for high sludge retention without compromising construction efficiency.
3. In combination with the special design of high dewatering efficiency, ACETube® allows quick turn over on-site and the limited space can be repeatedly used. Therefore, it makes possible to handle large amounts of sludge.
4. Due to the special design of the fabric and the correct use of the polymer, the filtrate is clearer than expected and can be recycled and reused.
5. The geotextile tube is placed for one month for dewatering and exposure. The moisture content of the sludge cake is rapidly reduced to 20%, that is to say, the dewatering efficiency is quite high.

What were the results of the project?

1. Time cost: It takes several years to use the tailings pond to directly precipitate and expose the sludge for concentration. In fact, the project is located in an area with limited space for work, and the geotextile tube only needs 4 to 5 months of dewatering treatment. The geotextile tube has demonstrated with success the reduction of time required for tailings dehydration.
2. Direct cost: The use of the geotextile tube eliminates the maintenance cost of the original dewatering machine and greatly reduces the cost of electricity; it is considered as the best balance between time and cost.
3. Indirect costs: The use of ACETube® allows to remove sludge quickly and at low cost, therefore it eliminates the cost and time required for the mine to build additional tailings.
4. Direct benefits: A large amount of sludge solids is retained, and the sludge cake can be resold for profit by enriching precious metals, making the waste a valuable commodity.
5. Environmental protection: The use of geosynthetics design, high efficiency recovery of filtrate and sludge cake, to avoid contaminating the adjacent environment of the mining area.

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