Services / Additional Golder PasteTec™ Services

Paste Rock

Conventional mine waste management systems produce both wet and dry waste streams. The wet tailings stream is commonly discharged as slurry that produces a segregated deposit with problematic drainage and seepage conditions, low shear strength and slow consolidation properties.

Impoundment design for slurry tailings is generally controlled by physical issues. The primary design philosophy is capacity, stability, containment and safety. However, numerous failures in tailings impoundments have occurred in recent times and it can be broadly stated that the primary concerns with tailings impoundments remain rooted in physical instability.

In contrast, the dry waste rock stream offers high shear strength with excellent physical stability characteristics and thus the material is routinely disposed of in large waste rock dumps constructed above the natural ground surface. While run-out failures in high, over-steepened dumps may occur, waste rock dumps typically form steep topographies with high stability.

The hydraulic properties of waste rock together with surface hydrology, internal structure and topography result in unsaturated conditions within waste rock dumps. Waste rock dumps constructed with tip faces greater than 4 to 6 m develop an internal structure associated with segregation producing coarse and fine layers with a high permeability rubble layer at the base.

The combination of unsaturated soil conditions together with the interbedded structure creates ideal conditions for weathering of the waste rock through geochemical and biological pathways. Sulphide oxidation and acid generation often begins during the construction of the rock dumps and results in long-term acid drainage and metal leaching, or other problems associated with neutral drainage and salinity.

Reactive tailings need to be protected from oxidation and this is normally achieved through sub-aqueous disposal that inhibits oxygen contact with the tailings. However, conventional sub-aerial disposal of reactive tailings as slurry can result in segregation of the tailings which leads to accelerated oxidation causing acid generation.

Golder PasteRock™ can blend waste rock and tailings to produce an engineered material, termed paste rock, with superior physical and hydraulic properties for the construction of post mining landforms. The new material also has a density much higher than either conventional tailings or waste rock deposits; thereby reducing the total volume of waste and creating opportunities to reduce surface area requirements for impoundment design and construction.

Backfill Contracting
& Operations / Mobile
Paste Plants

Golder PasteTec™ is an innovation leader in the development and use of mobile paste plants which can provide a lower capital alternative to the construction of a full paste plant facility.

Our engineers and operators develop a custom process for each project and address the unique characteristics of the feed material, the site location and the underground environment.

The mobile paste plants provided by Golder PasteTec™:

• Are fully transportable
• Are quickly assembled and dismantled
• Provide production rates up to 90 m³/hr of paste backfill
• Offer pumped or gravity injected backfill delivery
• Utilize single source or multi-blend paste recipes
• Have a consistent slump, from 5 to 10-inch available
• Can vary cement content depending on recipe

Golder PasteTec™ can supply the equipment, a paste engineer and site superintendent, QA/QC services, all laboratory testing, and mining/process engineering as required. The raw materials typically belong to the client or can be locally sourced.

Tailings Dewatering / Wastewater Management

Golder PasteTec™ provides a full spectrum of wastewater management and treatment services to mining and industrial organizations around the world.

Water is essential for mining and hydrometallurgical processes. However, the management of the water that results from the dewatering of tailings and disposal/storage of tailings and wasterocks often poses a major technological, environmental, social and economic challenge to the mining and mineral processing industry worldwide.

Golder PasteTec™ works with our clients to: reduce water use; prevent/minimize sources that can impact water quality; increase water recovery, reuse and recycle; and meet or surpass the regulated objectives for water discharge. As clean and potable water resources become scarce in the world, especially in Europe, Africa and Australia, water is rapidly becoming considered as a commodity. Thus, the optimization of a dewatering process makes a mining project economically viable as it will reduce the immediate and long-term environmental liabilities. In fact, many government bodies are stressing the importance of improved water use and are making this aspect of mining operations a stipulation of the permitting process.

By recovering the water from tailings and other waste products such as sludge, processing it and recycling it back into the mining and metallurgical processes, many mandated environmental, social and economic sustainable development requirements are achieved. The effective dewatering of tailings and sludge also reduces the foot print of the disposal/storage area. In addition, water reuse reduces the ever-increasing need for additional fresh water sources and can result in cost savings in a number of water management applications including environmental permitting, energy consumption, cost of equipment and water transportation.

The quality of water is critical when determining the amount available for recycle/reuse. Wastewater that results from operations at a mining or metallurgical site, including tailings water, drainage, and seepage water, can be alkaline or acid and may contain: salinity (e.g., anions of carbonate, sulphate, chloride, ammonium and nitrate, and cations of sodium, calcium, magnesium), suspended solids and metal ions such as iron, aluminum, manganese, zinc, nickel, copper, lead, arsenic and cyanide. Thiosalts, incomplete sulphide oxidation products that may cause delayed acidity in the receiving water reservoirs, may also be present. The quality of wastewater can vary widely depending on a number of factors such as the nature of the exposed minerals, the type of ore bodies, metallurgical processes used and climate.

The wastewater treatment services provided by Golder PasteTec™ include assessment, development, design and implementation of conventional “Best Available Economically Achievable” (BATEA) technologies as well as the use of emerging advanced technologies.

We are experts in designing and implementing chemical active treatment systems and passive treatment systems which can be used for a variety of flow rates in a variety of climates including extreme cold. Working in partnership with the water treatment services teams of Golder Associates allows us to provide a comprehensive level of service to address and identify potential issues and determine the most practical and cost-effective mitigation option for a given site.

Our water management and treatment services include:

• Assessment of water quality and treatment requirements
• Treatability studies
• Process development
• Pilot project completion
• Trouble shooting
• Process control and automation
• Conceptual design and detailed design
• Engineering, procurement, construction management (EPCM)
• Plant implementation and commissioning
• Staff training and creation of maintenance and operations (M&O) manuals