UQAT Evaluations of Solutions to Limit Wind Erosion on Tailings Impoundments (TPD1607057)

1.       Objective

• General objective: To develop methods to control wind erosion
• Specifics objectives:
  • To evaluate the performance of products that are commercially available to control wind erosion
  • To Study the extent of wind erosion on selected mining sites (before and after treatment)
  • To Develop tools to anticipate the level of wind erosion using numerical models

 

2. Tailings and Dust-Control Product Characterization

Receipt of 5 mine tailings

• 1 container of 1 m3 tailings from Doyon-Westwood mine,
• 2 barrels of tailings from Fonderie Horne site;
• 6 barrels of tailings from Éléonore mine;
• 6 barrels of tailings from Matagami mine;
• 16 barrels of tailings from Dumont projet;

– 8 dust-control products were received from 4 dust-control product suppliers

– Dust-control products were numbered from 1 to 8

 

Table. Product (Supplier) | Type

Tailings homogenization

 

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Physical and chemical properties of tailings

 

Table. Grain size distribution

 

 

Table. Specific Gravity (Gs)

 

FH and Matagami tailings are denser than other tailings

 

 

Table. Specific area

Dumont tailings specific area is higher than those of the other tailings studied

 

 

Table. Sulfur/carbon (S/C) content

According to Québec régulation on mine tailings (Directive 019), all tailings except Dumont tailings can be considered as acid generating tailings, since their S/C contents exceed 0.3% and the ratio NP/AP is less than 3.

 

Mineralogical properties of tailings

 

 

Table. Mineralogical properties of tailings

 

5 types of tailings dominated by:

– Silicates (97% for Éléonore tailings, 85%for Dumont tailings, 82% for Doyon tailings, 56% for Matagami tailings and 53% for FH tailings)

– Oxide (3% for Éléonore tailings, 15% for Dumont tailings, 4% for Doyon  tailings, 11%for Matagami tailings and 33% for FH tailings).

– Secondary minerals (gypsum in the tailings of FH (13%), of Doyon (13%) and of Matagami (8%)).

5 types of tailings contain very few sulfide except Matagami tailings that contain 25% of pyrite.

 

Rheological properties of dust-control product

The dust-control product rheological properties influence the ease of application and penetration of products in the pores of tailings

 

Table. Dynamic Viscosity (Pa.S)

 

Tailings preparation

Table. Testing water content:15% ± 2%

3. The protocol used

Tailings without dust-control product

Plate 1

Sun light exposure with UV lamps 1 Cycle (24h UV)

Compressed air jet test

Plate 2

Freeze/Thaw 10 Cycles (2h for freeze and 3-6h for thaw)

Compressed air jet test

Plate 3

Wet/dry under ambient air 5 Cycles (Wet/dry with deionized water)

Compressed air jet test

 

Tailings with dust-control product

Plate 1

Sun light exposure with UV lamps 1 Cycle (24h UV)

Compressed air jet test

Plate 2

Freeze/Thaw 10 Cycles (2h for freeze and 3-6h for thaw)

Compressed air jet test

Plate 3

Wet/dry under ambient air 5 Cycles (Wet/dry with deionized water)

Compressed air jet test

Tests in triplicate!

(Fan test replaced by compressed air jet test)

 

Tailings preparation

– Tests were performed in a plate of 19.5 cm diameter

– Fine fraction of tailings (sieving through 200 mesh to remove the aggregates from the tailings) were placed in the plate in a loose state

– Tailings layer with a thickness of 2 cm was placed in the plate at a water content of 15% ± 2%

– The tailings surface was leveled to ensure better application and penetration of the product

 

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Table. Rate application of dust-control product

 

Tested samples nomenclature

– Tailings were named A, B, C, D and E

– Plate + tailings without dust-control product were named A0, B0, C0 and E0.

– Plate + tailings with dust-control product were named A6, B6, C6 and E6 etc…

– 405 tests were performed (for all tailings and products)

     

Table. Product|Tailings

Conditioning: wetting/drying cycles

 

• Making holes in the bottom of the plats + Placing geotextile + placing tailings;
• Spreading the product on the tailings;
• Resting for 24h;
• Wetting the tailings with and without dust-control product with 200 mL per plate;
• Drying under ambient air for 48 h;
• Rewetting; 5 cycles are performed;
• Last cycle of drying is maintained for 7 days.

 

 

 

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Conditioning: freeze/thaw cycles

 

• Spreading the product on the tailings placed in the plate;
• Plate + tailings with and without dust-control product were left to stand for 48h;
• Plate +tailings were stored in a freezer at – 20 ° C ± 2 ° C to simulate freezing;
• Plate +tailings thawed at ambient air for 3 to 6 hours;
• Re-freezing; 10 cycles are performed on each tested tailings.

 

 

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Conditioning: Sun light exposure with UV lamp

 

• Plate + tailings with and without dust-control product were left to stand for 2 hours;
• Plates were installed under the UV lamps keeping a distance of 30 cm between the tailings surface and the lamps;
• Exposure time of 24 h was chosen and applied only once for each test.

 

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Appearance of Eleonore tailings surface untreated (A0) and treated with dust-control products (A6, A7 and A8) after 5 wet/dry cycles

 

Image. A0

 

Image. A6

 

Image. A7

 

Image. A8

Appearance of Eleonore tailings surface untreated (A0) and treated with dust-control products (A6, A7 and A8) after 10 freeze/thaw cycles

Image. A0

  

Image. A6

  

Image. A7

  

Image. A8

Appearance of Eleonore tailings surface untreated (A0) and treated with dust-control products (A6, A7 and A8) after 1 sun light exposure cycle

Image. A0

  

Image. A6

  

Image. A7

  

Image. A8

 

Comparison of the appearance of 5 tailings surface untreated after wet/dry cycles

 

Image. Éléonore (A0)

  

Image. F.H (B0)

  

Image. Doyon (C0)

  

Image. Matagami (D0)

  

Image. Dumont (E0)

– Presence of cracks on the surface of 4/5 tailings without dust-control product

 

Comparison of the appearance of the 5 tailings surfaces treated with product #6 (Soiltac) after wet/dry cycles

 

 Image. Éléonore (A6)

  

Image. F.H (B6)

  

Image. Doyon (C6)

  

Image. Matagami (D6)

  

Image. Dumont (E6)

– Formation of a highly resistant crust on the tailings surface

 

Comparison of the appearance of the 5 tailings surfaces treated with product #7 (Durasoil) after wet/dry cycles

 

Image. Éléonore (A7)

  

Image. F.H (B7)

  

Image. Doyon (C7)

  

Image. Matagami (D7)

  

Image. Dumont (E7)

 

– Product promote water retention in the tailings

– However, the tailings break up and disperse easily under the air jet test when dry

 

Comparison of the appearance of the 5 tailings surfaces treated with product #8 (Gorilla-Snot) after wet/dry cycles

 

 Image. Éléonore (A8)

  

Image. F.H (B8)

  

Image. Doyon (C8)

  

Image. Matagami (D8)

  

Image. Dumont (E8)

 

– Formation of a highly resistant crust on the tailings surface

 

Compressed air jet test

– Compressed air jet device was placed at 20 cm from the surface of the plate+ untreated and treated tailings with dust-control product

– Compressed air jet was applied with a pressure of 3 bar for 2 min

– The mass of the plate was determined before and after the test for determining the weight loss

– The surface of the plate+ untreated and treated tailings with dust-control product and its surroundings were observed carefully

 

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Compressed air jet test results

The following observation were made after the compressed air jet test:

– Detachments of particles;

– Possible detachment of layer when the product formed a thin layer on the tailings surface;

– Mass loss due to evaporation and particle detachment;

– The hardness of the tailings surface untreated and treated with dust-control product was tested by measuring the strength with a hand penetrometer.

 

The following weightings were used to describe the detachement:

0- Nil

1- Unimportant

2- Important

3- Very important

 

Table. Compressed air jet test results | Wet/dry cycle

 

 Table. Compressed air jet test results | Freeze/thaw cycle

 

Table. Compressed air jet test results | UV exposure cycle

 

Preliminary classification of the 8 dust-control products for the tested conditions

Table. Classification in order of effectiveness|Dust-control product ID

• In this presentation, only the results of wet/drying were presented, but the results of freeze/thaw and UV exposure are similar to those of wett/dry
• Dust-control products 6 and 8 were more effective than the product 7 (qualitatively) under the conditions tested in the laboratory (reasons: ?? will be investigate).
• The preliminary product classifications was presented without considering the costs.
• In further work, the first 5 dust-control products will be selected as specified in the agreement to:
• Evaluate the performance of dust-control products under various conditions using erodibility laboratory tests with PISWERL device
  • Evaluate the performance of dust-control products using column
  • test to assess the environmental behavior of products.

 

Thanks!