Services
Many organizations, including mining companies, encounter a number of complex environmental, technical, financial and social issues regarding their waste streams.
Golder PasteTec’s™ knowledge and capabilities can resolve these issues and assist organizations to operate successfully in today’s highly regulated business environment.
We offer a full range of services from mine review and waste audits, through laboratory testing and preliminary engineering to full detailed engineering, construction management and plant commissioning and training.
Our staff possess specialized and comprehensive knowledge of the properties of mined materials and their static and dynamic behavior. They use this understanding to provide optimum paste technology solutions that are designed with specific dewatering and transport engineering methods for each material.
Our team is organized into the following service groups:
Consulting Services
Golder PasteTec™ provides conceptual, pre-feasibility and feasibility level studies, optimization studies, capital and operating cost estimating, and backfill and surface waste disposal system audits. As well, we provide laboratory testing services including rheology index testing, binder strength testing, geotechnical testing, geochemical testing, underground production scale gravity flow loop testing projects, and backfill ground support testing.
Engineering
Golder PasteTec™ provides engineering services in all major disciplines (mining, instrumentation, process, civil, mechanical, electrical and structural) including process flowsheet development, conceptual preliminary design, detailed engineering, equipment procurement assistance and vendor bid analysis.
Construction & Operations Services
Golder PasteTec™ provides construction management, construction bid analysis, QA/QC and construction monitoring, commissioning, plant operator training, operation manual design, backfill and Surface Disposal system and commissioning and troubleshooting.
These groups work in conjunction with each other throughout all stages of the project life cycle.
Services / General Consulting Services
Golder PasteTec™ can define the concepts required to progress a project through the concept, pre-feasibility and feasibility stages of the project development process.
At the concept stage, many process and material transportation options are considered. Multiple technologies, scales of production, plant site and transportation corridors are optimized using sustainability, including technical, economic and environmental/social, criteria. This typically results in two or three design options.
The design options are carried forward and refined during the pre-feasibility and feasibility stages of the project. At the completion of the feasibility study, a preferred mineral waste management strategy will have been selected, the engineering design will have been refined and will have been costed to ± 40% accuracy.
The engineering designs are then optimized so that no fatal flaws are associated with the engineering project. These studies are completed according to international standards and are often used to obtain project financing.
The key strategic decisions at this stage of the project include whether buildings should be pre-engineered or custom designed, the final selection of instrumentation based on other control systems being utilized, and the tie-in to existing electrical systems.
Backfill Managements Plans
Backfill, in its various forms including paste, slurry and rock, involves the placement of large volumes of material that needs to be controlled within a stope boundary.
The design and implementation of a backfill management plan is essential in order to identify and manage the major hazards associated with the placement of backfill into stopes in underground mines.
The potential for high pressure and major inrush are key hazards that need to be addressed within the range of systems and controls outlined in an effective management plan.
Golder PasteTec™ has the capability and experience to be able to assist with the development, review and auditing of backfill management plans in underground mines. As well, our extensive experience and knowledge allows us to provide various levels of consulting assistance to operators thus ensuring a safe and efficient backfill operation.
Golder PasteTec™ can provide backfill management plans that will detail the planning, design, operations, monitoring, measuring and review processes for the following tasks:
- Organizational structure, responsibility and accountability
- Development of a risk register – hazard identification, controls and risk assessment
- Emergency response
- Quality control
- Monitoring, measuring, review and reconciliation
- Maintenance and inspection planning
- Mix design criteria
- Bulkhead design and construction quality control
- Testing requirements in the plant, underground and in a laboratory
- Mine and plant operational practices
- Integration into tactical and strategic mine design, planning, scheduling, mining and mill operations
Mine Site Backfill Materials Survey
To ascertain the availability of backfill materials and to complete the preliminary process evaluation, a site visit is usually appropriate to define the waste materials available to the mine site for use as backfill (rock, hydraulic slurry or paste fill). Golder PasteTec™ considers the mine tailings, alluvial sand, gravel, mine waste rock, etc. Mine geometry, mining methods, mill layout and related materials location including tailings pond, alluvial deposits and waste rock dump will all be reviewed. Suitable quantities of the different waste materials can be collected for later laboratory evaluation.
Backfill Mix Design
Based on the information obtained from a site visit or from information supplied by the mine (waste material size distribution and mineralogical and chemical composition), Golder PasteTec™ will define a backfill mix design. The mix design is dependent on the backfill method (rock, slurry or paste) chosen by the mine or dictated by material availability and/or waste management economics. The objective is to design a cost effective backfill mix that will optimize the chosen materials providing reliable underground distribution, minimal binder consumption and sufficient ground control.
Backfill and Surface Waste Disposal System Audit and Optimization
Backfill technology is continually improving existing underground backfill and surface waste disposal systems. Mine sites can benefit from a review to evaluate the efficiency based on production, waste management and long-term liability to the mine. Golder PasteTec™ will provide recommendations to improve the backfill quality and subsequently reduce costs. This can often be completed with minimal additional capital expenditure. In some cases, a larger review can incorporate a change in the waste management program, reducing acid mine drainage for example, or minimizing the mine’s liability with respect to its waste management.
Tailings Transportation
The successful transport of paste fill is very dependent on the quality of the paste. It must contain the correct mixture of tailings, cement binder and water components that must be uniformly mixed, free of lumps and at the specified slump. As well, the proper delivery system, using either gravity mode, pumped mode or a combination of both modes of transport, must be employed.
Virtually all tailings leave the extractive process in a slurry with the dry exceptions being gypsum (fertilizer industry – tailings sized crystals) and ash (power stations – fly and bottom ashes).
Defined as a non-segregating slurry, paste moves through a pipeline as a plug flow, exiting the line not as a liquid but as a semisolid resembling toothpaste. Its characteristics can be engineered to meet a wide range of considerations and circumstances.
Golder PasteTec™ can perform system analysis and design complete transportation systems for tailings transportation which will include analysis of and sourcing of equipment (including belt conveyors, stackers, hoppers, feeders, transfer towers, piping systems and pumps), conduct Flow Loop Testing Projects, analytical pressure modelling, life cycle costing and contingency planning dealing with secondary spill containment.
The selection of the transportation method is an integrated decision involving:
- The capital and operating cost of the system
- The demands placed on the system – volume, rate, head, distance
- The pumping system required – conventional centrifugal pumping or positive displacement pumping
- The environmental limitations of the Tailings Storage Facility (TSF)
Rheology Index Testing
The specific rheology of the backfill materials (tailings, waste rock, etc.) will be characterized using laboratory index tests developed by Golder PasteTec™. The index tests will be used to define the potential backfill materials suitable for underground gravity transport/pumping as a hydraulic slurry or paste fill. Similar tests can be conducted to determine the transport properties of a given waste material for Surface Disposal.
Binder Strength Testing
Golder PasteTec™ can conduct binder strength tests for a given backfill method. The materials are tested using a specific binder (Portland cement, fly ash and slag cement). Test cylinders are cast (diameter to accommodate the given fill material particle size, usually 4u) to develop a uniaxial compressive strength versus binder content relationship. Through the use of the Golder PasteTec™ backfill database and analytical and numerical analysis, the required backfill strengths for a specified backfill performance (i.e. cut & fill mucking floor, self-supporting backfill head cover, free standing wall height, etc.) can be optimized for a given mining geometry.
Similar test work can be conducted to evaluate efficiently the use of different types of binder, backfill materials and/or backfill methods for a specific mine site. Strength tests can also be conducted to determine the binder concentration required to ensure stable surface waste disposal sites for a certain site geometry.
Backfill Ground Suport Testing
The geo-mechanical properties of a given mine fill material (rock, hydraulic slurry, or paste fill) can be determined from the triaxial compressive testing of backfill cylinders. Porosity, Young’s modulus, Poisson’s ratio and stiffness of the fill material at different confining pressures will be determined by this test work. This data can be used to evaluate the ground support properties of the material and thus determine, through analytical and numerical analysis, if the fill material can provide the strength required by the given mining situation.
Geotechnical Testing
For surface disposal, Golder PasteTec™ conducts a series of tests to determine the properties of the material once placed on the surface. These include tests specifically developed to assess the change in material characteristics of the tailings (such as density, moisture content, sedimentation and permeability) when deposited.
Geochemical Testing
Many paste properties are influenced by the mineralogical and chemical make-up of the tailings. In addition, more specifically for surface disposal, leachate quality and acid generating potential need to be determined.
Surface Pump Loop Rheology Testing
Surface flow loop testing projects can determine the rheological properties of a hydraulic slurry or paste material (75 to 85 wt% solids). These tests can be performed by Golder PasteTec™ using one of several test systems available at our laboratory or directly at the mine site.
These tests, which can be performed in a 4”, 6” or 8” diameter pipeline system, can be conducted for underground backfill or surface waste disposal materials. The data collected is essential for the engineering design of the Surface Disposal pumping/pipeline system or borehole/pipeline underground gravity flow distribution system.
The test work requires up to 10 m3 of material which is prepared to the relevant pulp density or slump consistency then fed through a pump and circulated through the instrumented flow loop at varying flow rates. The data logged pressure drops per length of pipeline for a given diameter pipeline. The different flow rates are analyzed and an average pressure loss per length can be determined for the tested material. The results of the analysis will be used to confirm the laboratory characterization of the material obtained from the laboratory rheology index testing and to design the distribution system.
Underground Production Scale Gravity Flow Testing
Golder PasteTec™ can provide testing for potential mine backfill materials at the mine site using an existing or simulated production scale underground gravity flow borehole/ pipeline system. This testing is conducted to produce more precise pressure loss data with which to design a given underground borehole/ pipeline distribution system for hydraulic slurry or paste backfill.
