What Environmental Problems does the Industry Face in Ore Processing?Mon, 10/22/2018 - 10:37
Ore processing is one of the most important steps in extracting ore. Correct processes can make all the difference in increasing the amount of minerals that can be extracted from the rock. But the best way to extract metals remains sodium cyanide, a toxic chemical that is often blamed for pollution of rivers and lakes after tailings dam spills. Mexico Mining Review interviews sodium cyanide suppliers, operators and environmentalists to understand the importance of sodium cyanide, the best practices for its use and evaluate the alternative technologies that are now emerging to challenge it.
The people that use sodium cyanide want to optimize their gold recovery. To avoid a drop in recovery levels, they often prefer to err on the high side of concentrations and use more cyanide than necessary. Our proprietary Cyanide Control System technology allows companies to remove this variation and be more precise and effective when it comes to recovery levels. There is a sweet spot when it comes to the use of sodium cyanide, using too much cyanide can cause cyanide solutions to leach unwanted metals and using too little can drop recovery rates. This is where technology and applications can play an important role. Our tools are advantageous because they are easily incorporated into systems that are already fully automated.
According to citizen surveys, the greatest worry regarding mining activities is related to water use. People often think that because miners use hazardous substances such as cyanide, they want to get rid of them. But more often miners actually want to get these chemical components back so they can reuse them. These are released accidentally, but not through daily operations. Most of the allegations we receive are on water contamination concerns, usually based on speculation and with no support from further research such as from COFEPRIS regarding cancer incidence in a mining area.
Just prior to the finalization of our acquisition of San Dimas in Durango, there was an unfortunate spill caused by a series of breakdowns. It was mainly due to a failure of the onsite workers, whereby a truck driver left the truck abandoned on a hill and left the site. This truck was full of water that contained cyanide and the valve on the truck was rusted and began to leak. The contents spilled into the river. This had an impact on the fish in the river. This should not have happened but it is difficult to prevent things like that. All we can do is provide training and hope employees follow company policies and best practices. This is just one example where it is necessary the state governments work with industry to deal with issues that arise regularly.
Many operators are struggling with grades that are not as high as they used to be, which affects their ability to maintain their production levels. This means the industry needs to use chemicals in more efficient ways to maintain production levels. Our plan is to help the industry take better advantage of the power of chemistry to improve their operations, and we are using our knowledge in chemistry to find innovative solutions for lower grade operations. Each mine represents a unique opportunity to better measure systems and create a more efficient output. As lower grades become a growing reality, measurement technology will continue to play a bigger role in the processing circuit. It is important to analyze and use mega data trends to predict output. Our customers need help with prediction the production output based on certain grades and the effect sodium cyanide can have on these.
We find that Mexican standards to avoid spills are good, but some mining companies do not want to follow them as they are expensive and miners believe they can avoid accidents by themselves. Spills are often related to design and construction of mines and the industry lacks quality control in this regard. On the other hand, overregulation can be detrimental for the industry as it can hinder business development. But by constantly monitoring macroinvertebrates in water bodies we can accurately evaluate the impact that mine operations have in the areas surrounding them.
Large scale mining of precious metals often involves the use of toxic materials and also consumes large amounts of energy and water. In addition, the tailings produced by a minefield typically contain significant amounts of the sought-after metal, though it is usually not economically feasible to treat the tailings to obtain the remaining metal. These metals can be damaging to waterways and other portions of the environment if released. Although these precious metals have high value, the high cost and difficulty involved with water treatment severely limits any current practical plan to fully extract the value of these streams. Accordingly, more efficient and greener methods of recovering precious metals from waste streams would be beneficial to mining operations, wastewater treatment plants, and municipal agencies.
AmmLeach®, which is our core technology, is very similar in terms of methodology to conventional acid leaching. However, the most important difference is that we are using an ammonia reagent. AmmLeach® that has significant economic, environmental and efficiency benefits. The important thing to note is that the same equipment can be used, with no need for elevated temperature or pressure. Yet by using our patented technology with incorporating a pre-treatment step, in many cases the targeted metals can be recovered in a much more cost-effective way than using acid leaching. This is not suitable directly for gold and silver projects but it is certainly suitable for base-precious metals mixed deposits, such as gold-copper or silver-zinc.