Transform Mining Towards a Zero Waste Industry

Energy/Processing

This technical group comprises thought leaders from the mining sector and is led by Chair Simon Hille, VP Technical Services, Goldcorp and Rob Stephens, Director Applied Research & Technology Teck. In 2015, the CMIC Energy and Processing groups amalgamated as two of the top three challenges to tackle were identified by both groups. A summary of activities is described below.

Mineral Processing Roadmap

Thought leaders from the industry, assisted by Hatch and MDM Consulting, created an industry level technology roadmap for mineral processing.  This roadmap is a plan that matches short-term and long-term goals with specific technology gaps that need to be solved.

The development of this roadmap helped to reach a consensus about long-term goals in a 10 to 20-year time frame, a set of needs and the technologies required to satisfy those needs.  It provides a framework to help plan and coordinate technology development across the mining sector.

At an industry level, this roadmap will accelerate solution development and deployment as it helps to focus efforts across the ecosystem from academia to start-ups to SMEs, both inside and outside of mining.

To the best of our knowledge there has never been a consistent effort to create industry-wide technology roadmaps for mining, until now.

The next step for CMIC will be to further establish and communicate these common innovation priorities and opportunities for the mining industry and engage with stakeholders to refine and implement this technology roadmap through workshops further enabling collaborative innovation projects and partnerships.

Transforming Grinding in the Mining Industry

Comminution, the fine grinding of solids, is employed by many industries to achieve desired chemical and physical properties. It is estimated that 3% of the world’s electricity is consumed in comminution processes.

The grinding process results in significant energy loss. Less than 5% of the energy input is employed for the actual breaking of the particles. The remaining 95% is heat loss at relatively low temperatures, otherwise known as low grade waste energy. This is a common challenge in the mining industry with as much as 50% of energy used in the mining process lost as low-grade waste energy during a number of processes, including as air is ventilated, as water is discharged from the mine, and during tailings discharge.

With energy accounting for an average of 15–22% of total mine operating costs, significant innovation advances in comminution alone can yield major advances in energy efficiency, cost and emissions reduction with the use of new technologies.

To identify suitable emerging technologies for collaborative development, CMIC contracted Hatch to appraise new and existing comminution technologies.  The study concluded that Conjugate Anvil Hammer Mill (CAHM) technology was the optimum choice for collaborative development.

The proposed CAHM machine development path will include a short-term study and a long-term plan.  The short-term study (6 months) is focussed on addressing questions regarding basic operational parameters.  In the long term (3 years), the CAHM operation and performance needs to be validated by means of pilot testing of a CAHM prototype machine.

Comminution Technology Appraisal Study

The objective of the project was to provide a well-rounded assessment of existing, emerging, typical, and non-conventional technologies in comminution. The appraisal takes into account technology readiness, engineering and cost considerations.

Low Grade Waste Energy Recovery Technology Prefeasibility Study

Low grade energy, defined as a waste stream below 2320C, is often discharged, because it is not economical to recovery, upgrade, and reuse the energy. However, with new technology advancement and increasing fuel prices to generate power, recovering energy recovery has become more attractive and practical. In addition, power generation is and will remain a strategic issue in the future that will govern the way mines operate in certain regions. The opportunity to reduce energy cost and utilize waste energy within mining operations can influence strategic planning and allow mines to dissociate from fluctuating global prices for energy, reducing risks and ensuring stable and profitable long-term operations.

In this project, technologies that can be applied in the mining industry were identified, categorized, and evaluated to aid adoption by members of the Canadian mining industry. Waste energy can be recovered and applied in several aspects, such as directly reused for heating or cooling, power generation, and in hybrid systems.

The project includes a written summary and a Microsoft Excel based CMIC Waste Energy Technology Matrix. The written summary outlines the methodology used in this study, an overview of each technology identified, selected case studies, and next steps to move from the study phase to implementation phase. The Technology Matrix is a tool to help industry members identify waste energy recovery technologies that can be applicable to different mine sites. This tool describes each identified technology briefly, outlines the heat source and heat sink, sets technology readiness level, and provides cost information.

 

Mapping Energy Losses in Grinding Circuits

 

The objective of this project was to develop a modelling tool to identify the potential for recovering energy losses in grinding circuits. More specifically, the tool will provide an estimate of the distribution of sources of thermal, sound and vibrational energy.

CanmetMINING and CMIC proposed a 5-step project to complete the energy study of three (3) grinding circuits and to develop an MS Excel tool to allow mining operators to identify energy losses. Agnico-Eagle’s Goldex and Canadian Malartic mines, and New Gold’s New Afton Mine participated in the study by providing operating data for 3 semi-autogenous grinding (SAG) mills and 4 ball mills.

The development of the model was based on an article by Radziszewski (2013) suggesting identifying energy losses during grinding using a thermodynamic model. This approach was used to estimate the heat dissipated by the electrical and mechanical equipment, the heat dissipated through the shell of the mill by convection and radiation, the latent energy absorbed by water during evaporation and the grinding work which includes ore crushing, ball and lift plate wear, plastic deformation of the structures and the sound and vibrational energy.

The tool to identify energy losses in a wet grinding circuit was delivered to CMIC. Despite the complexity of the processes and the difficulty in measuring slurry temperatures, it is relatively easy to determine a circuit’s detailed energy balance. Data from the three grinding circuits studied show that on average 77% of the electrical energy supplied to the grinding circuit is transmitted to the slurry, the grinding work accounts for 10%, 8% is lost through the drive system and about 5% of the energy is transmitted to the ambient air around the grinding mills. This means that approximately 90% of the thermal energy is potentially recoverable. Only one production datum is required, which is the electric power of the grinding mills.

Read the full report.

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