Halyard's Tailings Reclamation: An Industry ModelBy Alejandro Ehrenberg | Tue, 06/30/2020 - 14:02
Q: What trends are shaping tailings management worldwide?
A: The more responsibly a company behaves, the better chances it has of surviving and growing. Social issues are at the forefront of the mining industry’s risks and opportunities. There has been a shift of power toward civil society and away from the big corporations. Tailings management is one of the most important social and environmental issues facing the industry. One of the ways of mitigating risk in this area is through the use of new technologies. For example, companies are adopting new monitoring methods based on IoT and cloud technologies. Also, economic and environmental considerations are making tailings management more acceptable in the long term by improving the safety thereof and reducing the risks. Stakeholders are concerned about the liability of having tailings dams, so there is a financial incentive to lower the risk.
Historic tailings are an often-neglected aspect of all this. These tailings may present the opportunity to extract valuable minerals while simultaneously providing social value. Companies and governments now have the opportunity to correct historical issues at tailings dams that were built without the benefits of current technology.
Q: What are the main characteristics of the project you are undertaking at a historical tailings dam in Newfoundland?
A: The project in Newfoundland is very isolated, it is subject to bad weather and it has a small labor force. The mine was in operation from 1929 to 1986, leaving a tailings dam there. Mining properties in Canada are often owned by the government as they occur on Crown Lands. As is always the case, the company had leased the property and paid for the reclamation. But long after the company had left, the government started noticing structural problems with the dam’s stability. Together with a private mining company, they developed a project to remediate it during the course of which valuable minerals were subsequently recovered. This entailed the extraction of barite from the old tailings. With the help of Halyard, the company will make a profit from extracting the valuable materials and will co-finance the project to remediate the site which is a benefit to the local community and the government.
The technical side was quite complicated. Halyard’s engineers lowered the water level in the dam. We then designed a machine to dig up the tailings for processing. We dry the tailings, mix them again with water and, by means of gravity separation and flotation, we extract barite and residual sulfide material. Finally, we take the processed tailings and safely redeposit them in a different area of the existing tailings dam. In the future, they can be stored in a dry stacking method.
Q: What is the applicability of this to Mexico and how can Mexico benefit?
A: Mexico has a long mining tradition and its historic tailings deposits can benefit enormously from these types of interventions. One of the attractive things that the government of Canada saw in the Newfoundland project is the region's vibrant offshore oil industry. Barite, the mineral we are recovering there, is used in the oil and gas industry as a weighting material in the formulation of drilling mud. Similarly, a major business opportunity for miners exists in Mexico for the recovery of barite from tailings; barite can then be delivered to the local offshore oil and gas industry in the Gulf of Mexico and South America. Barite is commonly associated with zinc and lead operations. Mexico is a major producer of both minerals.
A project like the one we are carrying out in Canada allows private companies and society to benefit from not having an environmental liability in the form of historic tailings deposits. The local oil and gas industry benefits from having a domestic barite supplier. Reprocessing tailings may be expensive but if some of the value in the minerals that can be extracted can pay for the reclamation, then there is a good financial argument for it.
The ecological benefits are clear. Older tailing dams were not built with consideration to long-term environmental impact. If we can reprocess these sites, we can deposit the material in a dry stack, cover it up so it is not exposed to air and repurpose the site for agriculture or other productive uses.
Q: What problem can Halyard help solve when designing tailings management in greenfield projects?
A: One of the top considerations regarding tailings today is the fact that the world is in short supply of freshwater. A method for tailings disposal that uses less water is of great added value. There are dry methods for disposing of tailings, but they are more expensive than traditional methods because they require more energy. Nevertheless, the long-term benefits of dry tailings are that the waste is more stable and that water is recovered. Any new facility will have to be designed in a manner that is mindful of water. Halyard is well-positioned to design tailings solutions that can be mutually beneficial and comply with modern standards. Our experience comes from the numerous projects that we have worked on. We can assist our clients in terms of technical and cost constraints. We also have a good database for clients to use when carrying out their technical and economic evaluations.
Halyard serves the mineral processing, water treatment and utility segments, offering its clients a team of multidisciplinary engineers, project managers, designers and project support experts. Halyard’s key services include project management, engineering, design and implementation of mineral processing plants.