Process of preparing a cemented paste backfill material
A process of preparing a cemented paste backfill material, the material including ground mine tailings, a hydraulic binder and water, wherein the solids content of the backfill material is 70-82 wt.-%, the process including a) providing a dry premix, the premix including the hydraulic binder, a superplasticizer and optionally a defoaming agent, b) mixing the dry premix with the ground mine tailings and water.
1. A process of preparing a cemented paste backfill material, said material comprising ground mine tailings, a hydraulic binder and water, wherein solids content of the backfill material is 70-82 wt.-%, the process comprising:
a) providing a dry premix, said premix comprising the hydraulic binder, a superplasticizer and optionally a defoaming agent,
b) mixing said dry premix with the ground mine tailings and water, wherein the premix is provided in powder form.
2. The process according to claim 1 , wherein the hydraulic binder comprises Portland cement.
3. The process according to claim 1 , wherein the hydraulic binder comprises ground granulated blast furnace cement at a content comprised between 70 and 90 wt.-% of the total hydraulic binder, or fly ash between 40 and 70 wt.-% of the total hydraulic binder.
4. The process according to claim 1 , wherein the amount of dry premix is selected so that the backfill material has a content of hydraulic binder of 2-14 wt.-%.
5. The process according to claim 1 , wherein the dry premix additionally comprises a stabilising agent.
6. The process according to claim 1 , wherein the superplasticizer is a phosphonate based admixture, or a polycarboxylate ether based admixture.
7. The process according to claim 6 , wherein the dry premix comprises 0.5-10 wt.-% of a polycarboxylate ether based superplasticizer.
8. The process according to claim 6 , wherein the polycarboxylate ether based superplasticizer has a charge density of >1.5 meq/g.
9. The process according to claim 6 , wherein the dry premix comprises 0.5-10 wt.-% of a phosphonate based superplasticizer.
10. The process according to claim 1 , wherein a polyether is used as said defoaming agent.
11. The process according to claim 10 , wherein the dry premix comprises 0.05-2 wt.-% of a polyether based defoaming agent.
12. The process according to claim 5 , wherein the stabilizing agent is a diutan gum.
13. The process according to claim 5 , wherein the dry premix comprises 0.2-2 wt.-% of the stabilizing agent.
14. The process according to claim 1 , wherein the mine tailings have a solid content of 70-82 wt.-%.
15. The process according to claim 1 , wherein the mine tailings are from a mine extracting at least one of gold, silver, copper, zinc, uranium, platinum, palladium, nickel, beryllium, cobalt, chromium, gallium, indium, lead, lithium, magnesium, manganese, molybdenum, aluminium, barium, antimony, bismuth, tantalum, titanium, tungsten, vanadium, iron, diamonds, sapphires, opals, emeralds, rubies, graphite, alexandrite, aquamarines, spinel, topaz, cadmium, potash, a rare earth element and a platinum group metal.
16. The process according to claim 1 , wherein the solids content of the backfill material is 74-80 wt.-%.
17. The process according to claim 4 , wherein the amount of dry premix is selected so that the backfill material has a content of Portland cement of 2-14 wt.-%.
18. The process according to claim 4 , wherein the amount of dry premix is selected so that the backfill material has a content of hydraulic binder of 3-6 wt.-%.
19. The process according to claim 7 , wherein the dry premix comprises 1-6 wt.-% of a polycarboxylate ether based superplasticizer.