Backfill Binder System

Backfill Binder System

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Introduction to Backfill

System –

The backfilling provides ground support and regional stability, thus facilitating ore removal from nearby regions. The large underground voids created by the ore removal are
backfilled with the waste tailings in the form of paste fills, hydraulic fills, and others. The tailings are placed in the form of slurry that undergoes self-weight consolidation. A small dosage of binder is added to paste fill and cemented hydraulic fill to enhance strength. Considering the high cement cost, mines are using fly ash and slag to partially replace cement with blended cements.

There are several key parameters that must be evaluated to understand which type of fill can be applied on a mine.

• Enabling a more complete extraction of the ore body

• Environmental constraints

• Management of surface subsidence

• Minimising waste-rock dilution

• Promotion of mine stability

• Reducing the volume of waste hauled to surface

• Recovery of remnant ore pillars

• Surface disposal limitations

  Several types of backfill can be applied :

  Rock Fill

• Placement of waste rock into the mining void. Generally undertaken using trucks and gravity, but sometimes placed or pushed up using LHDs

• Development or run-of-mine waste (sometimes imported waste)

• Load Haul Dump (LHD) loaders, haul truck or conveyor

• Suitable as a working platform or for secondary stopes. Cannot be exposed vertically or under-cut

• Little quality control, highly variable particle size

• Relative cost: Low 

            Cemented Rock Fill

• Cementitious slurry applied to waste rock. Systems vary but slurry is added to the waste rock, is mixed, and then placed into the stope using a truck or LHD

• Ideally crushed and screened rock, development, or run-of-mine waste (sometimes imported waste). Particle size optimisation required to maximise particle-packing density

• LHD or haul truck. Cementitious slurry via agitator truck or slickline from surface

• Possible to achieve strengths >4 MPa depending on mix. Vertical exposure

• Size manipulation, mixing systems and deposition method greatly affects the final product quality

• Relative cost: Low to High. Trade-off between capital and operating costs

• Excellent for: Filling voids which will be exposed during future mining

             Hydraulic fill

• • Hydraulic disposal of tails into stope, with or without Solids will settle and require topping up to full on several occasions. Fill fence or weep-bags designed to allow water to escape

  • Coarser than paste fill. Often requires hydro-cyclone (or similar) to modify Particle Size Distribution (PSD)

  • Reticulated from surface. Contained behind fill fence or in weep-bags

  • The backfill dewaters during placement so increases demand on mine dewatering system. Requires topping up as backfill dewaters. Water cannot be allowed to accumulate in the stope as  this poses a risk of failure or inundation to the mining operation

  • Good quality control possible, susceptible to binder segregation during dewatering

  • Relative cost: Low cost for a hydraulically delivered product but cement cost is high when required

  • Excellent for: Establishing working platforms and vertical exposure where mine water is not considered a problem

    Paste fill/ Cemented aggregate fill

  • Binder added to whole-stream tailings, with or without aggregate and reticulated into the mine void

  • Minimum 15% passing 20 μm

  • Reticulated from surface. Contained behind fill fence or weep-bag

  • High quality control, homogenous product

  • Relative cost: Capital cost generally higher but operating costs lower than for hydraulic fill. Costs must be traded off vs backfill quality

  • Excellent for: Stabilising voids and backfilling workings and filling voids which will be exposed during future mining exposures

Advantages of using Ecostar

• Conventional backfill binders bleed at a rate
  between 29 to 36%. Ecostar is currently at 18% to 22%. Based on the 18% to 22% bleed, that is approximately 15% more gained backfill volume underground.

• Efficiency % per ton of backfill placed is currently 80%.

• Phase 2 of the product will have a 100% efficiency of backfill placed

• 100% locally manufactured product.

• Flow rate is approximately 6.9 seconds.

Ecofill – Backfill Binder System

• Higher compressive and flexural strengths

• Better flow rate

• More economical

• Superior chemical resistance

• Lowers hydration tempratures

• Reduction of pump-line pressures

• Quicker mixing per batch

• Reduced production times

• Removal of toxic pollutants

• Removal of chemical burns within cementitious systems

• This system requires any type of cement based on
  strength requirements mixed with ecofill to give the desired results.

Ecostar (see MSDS and TDS)

Need a TDS
Ec0star complies with the 32.5 specification when tested as per SANS 50197.

Ec0star achieved strengths of approximately 5.7MPa for 28 days by using 8% of binder with a tailings of 25% passing 25 micron.

Arc Innovations has a delivery capacity of 8-10 trucks per day. Each truck has a capacity of up to 32 tons meaning that Arc Innovations can deliver around 250 – 320 tons per day.

Conventional backfill binders bleed at a rate between 29 to 36%. Ec0star is currently at 18% to 22%. Based on the 18% to 22% bleed, that is approximately 15% more gained backfill volume underground.

The efficiency % per ton of Backfill placed is currently 80%. Arc Innovations have already start- ed to look at ways to make improvements on the product. The phase 2 product that is currently being finalised will have a 0% bleed that is required to attain tight-fill and reduce the amount of water seeping through the rock or into excavations. This has also been tested and verified at external laboratories.

The higher bleed of backfill placed results in more water accumulating underground. This means that larger volumes of water will require pumping resulting in higher maintenance on pumps. Bleed water running through fissures cause disruption to other underground works thus lowering the production rate of the mine. The movement of the material through fissures also require additional amounts of backfill to be placed. This was one of the crucial aspects that Arc Innovations experienced underground.

Mining Charter Compliance

There are many advantages of purchasing Ec0star in terms of the Mining Charter Compliance as Ec0star is a 100% locally manufactured product and Arc Innovations are a level two B-BBEE compliant company with 65% black ownership.

Flow Rate

The flow rate of Ec0star is approximately 6.9 seconds.

Benefits Of Using Ec0Star

• Strengths of 5.7MPa achieved for 28 days using 8% binder.

• Product complies with 32.5 specification when tested as per SANS 50197.

• Efficiency % per ton of backfill placed is currently 80%.

• A 100% efficiency of backfill placed can be achieved in the phase 2 of the product.

• Currently 15% more gained backfill volume underground compared to conventional backfill binders.

• Ec0star is a 100% locally manufactured product.

• The flow rate is approximately 6.9 seconds.

Ecostar TDS

Description

Ecostar is a propriety blended cementitious material designed to be blended with mine tailings to achieve stable backfill.

Typical Uses :

Ecostar is a typically used in backfill operations to achieve a stable backfill product in a weep or non-weep system.

Further benefits are:

• Ability to set and strengthen in low waterflow.

• Low bleeding.

• Good flowability and pumpability for long durations.

• Low pump pressures.

• Low carbon footprint.

• Increase production achievable with the same labour force and equipment.

  Special Features :

  Ecostar increases fluidity and lubrication in underground pipeline systems.

  Limitations :

  Ecostar should not be used in an unventilated environment.

  Physical Properties :

  Please read MSDS in conjunction with the TDS.

  Packaging :

  30kgs Bags or bulk tanker

Storage :

Keep in bulk silos or cool containers off the ground.

Shelf Life :

6 months if correctly stored.

Technical Advice

The technical department is available to assist with advice on the correct application of the Ec0Star.

Ecofill

• Contractors at a site that is using Ec0fill as a backfill grout binder have reported the following benefits of using Ec0fill compared to fly ash:

  • The placing of the blasting materials can take place simultaneously while grouting without the presence of Ammonia
  • The ammonia smell above ground at the grout mixing plant has being
  • A reduction of the caustic nature by a factor of 200 times of the support grout has meant that there are no chemical
  • A reduction of carbon footprint from ±280 CO2/m³ to ±100 kgs.CO2/m³
  • A reduction of carbon footprint equivalent of 1440t of CO2 per month
  • A shortening of mixing time of approximately 10 seconds (15%).
  • Pumping of a higher density material means that support packs can be completed 40%
  • An overall increase of production estimated at 20 to 30%.
  • Blasts have occurred at 45 minutes after completion of the pack without requiring the pack to be re-pumped.
  • A reduction of pipeline pressures of 20 – 25%
  • A significant reduction of plant