UQAT Evaluations of Solutions to Limit Wind Erosion on Tailings Impoundments

A. Sylvette, PH.D.; I. Hane, Msc.; M. Mbonimpa, ing., PH.D.
2016-07-01
URSTM, United Research and Service in Mineral Technology

L’UQAT, l’université au cœur des mines

DÉVELOPPEMENT DES CONNAISSANCES

Evaluation of Solutions to Limit Wind Erosion on Tailings Impoundments

Performance of Dust-Control Products Using Index Tests in Laboratory: Dust-Control Product Pre-Selection

By

A Sylvette, PH.D.

I Hane, Msc.

M. Mbonimpa, ing., PH.D.

Juillet 2016

Plan

1. OBJECTIVE

2. TAILINGS AND DUST-CONTROL PRODUCT CHARACTERIZATION

  • Tailings and dust-control product receipt
  • Tailings charateristics
  • Rheological properties of dust-control

3. DUST-CONTROL PRODUCT PRE-SELECTION TESTS

  • Protocol used
  • Tailings preparation
  • Tailings curing conditions
  • Compressed air jet test

4. CONCLUSION AND FUTURE WORK

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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

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Table. Product (Supplier) | Type

Tailings homogenization

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Physical and chemical properties of tailings

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Table. Grain size distribution

 

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Table. Specific Gravity (Gs)

 

FH and Matagami tailings are denser than other tailings

 

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Table. Specific area

 

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

 

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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

 

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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

 

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Table. Dynamic Viscosity (Pa.S)

 

 

Tailings preparation

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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)

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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

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Image. A0

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Image. A6

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Image. A7

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Image. A8

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

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Image. A0

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Image. A6

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Image. A7

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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

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Image. A0

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Image. A6

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Image. A7

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Image. A8

 

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

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Image. Éléonore (A0)

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Image. F.H (B0)

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Image. Doyon (C0)

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Image. Matagami (D0)

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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

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 Image. Éléonore (A6)

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Image. F.H (B6)

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Image. Doyon (C6)

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Image. Matagami (D6)

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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

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Image. Éléonore (A7)

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Image. F.H (B7)

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Image. Doyon (C7)

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Image. Matagami (D7)

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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

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 Image. Éléonore (A8)

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Image. F.H (B8)

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Image. Doyon (C8)

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Image. Matagami (D8)

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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

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

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

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Table. Compressed air jet test results | UV exposure cycle

 

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

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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!

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