Courtesy of Doris Hiam-Galvez

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Doris Hiam-Galvez, director of metals at Hatch, can envision a day when more mining is done without the need for haul trucks, waste rock or tailings storage. How? In-situ recovery (ISR), also known as in-situ leaching, is a less invasive mining process that is routinely used for potash and uranium today, and could eventually be applied to some of the deep, hard rock ores hosting copper, gold and other minerals. As ISR technology and experience advance, so too does the prospect of more mining without the environmental and economic costs associated with big open-pit mines.

CIM: What was the career path that led to your current position?

Hiam-Galvez: I’m from Peru originally, and I completed a PhD in physical metallurgy in Belgium. I then went to the U.S. for my first job, where I worked developing new materials for the steel and automotive industries. I moved on to the aluminum industry as CTO for Novelis. I came to Canada and started working for Hatch as director of metals. I’ve been there for 12 years leading the expansion of the company around the world, in Australia, South America, and Europe. I started our ISR efforts while I was running Hatch Europe.

CIM: What is ISR and how is it different from open-pit mining?

Hiam-Galvez: Traditionally we mine by digging a big hole in the ground and separating the valuable minerals from the waste. With in-situ leaching, you are going where the mineralization is, you’re fragmenting the rock and trying to get the leaching solution to go into the mineralization and extract it as a leached solution. You don’t need to dig a big hole, but instead, dissolve the valuable minerals underground and pump it to the surface. So it’s an alternative method to extract valuable minerals without physically mining the rock, something comparable to laparoscopic surgery where you don’t make a big wound or mess, just a tiny hole.

CIM: For which minerals is this recovery process currently applied?

Hiam-Galvez: These technologies have been used for many years for potash and uranium because it is found in porous rock that is not very deep. ISR has also been used for shallow, highly fractured copper oxides, for example, at BHP Billiton’s San Manuel copper mine in Arizona. They produced copper for about five years.

CIM: What are the environmental benefits of this approach?

Hiam-Galvez: When you do comminution, you have to bring everything up and out of the ground: the valuable mineralization of the rock and all the waste. Most of mining is just getting from a boulder to powder. With ISR, you take only what you need and you can then use smaller infrastructure above ground to finish, to recover the copper or valuable material. So you eliminate crushing, grinding and all the heavy equipment with minimal tailings and waste.

CIM: What are the future opportunities using this approach, and what are the challenges?

Hiam-Galvez: ISR is not focused just on one mineral or metal, but copper is very abundant and the price is good, so there’s a lot of interest in applying it to copper right now. The big challenge is for ores hosted in unfractured rock deep underground, including copper sulfides, gold, and others. The challenge is that rock permeability and porosity have to be enhanced to expose the minerals to the leaching solution, and how you do it depends on the specific ore body characteristics and the mineralization.

CIM: So this is not a one-size-fits-all solution. How you do it will depend on the specific ore body.

Hiam-Galvez: That’s correct. You have to develop an ISR process for each ore body to fit the physical characteristics. But there are flexibilities to its use, as well. For example, consider an open pit near the end of its life. It may not be economic to recover value from the walls of the existing infrastructure, but you can do ISR with minimal waste or tailings. So this can be applied to the walls of an existing mine. Also, if you already have an open pit and you are going underground, you are already deep down, so if you just go a little further underground, you can start with ISR. There are many different ways to apply this.

Related: The development of a technology to assess the risk of self-heating sulfides

CIM: How do you prepare an unfractured ore body for ISR?

Hiam-Galvez: You have to prepare the mineral to be liberated – the chemical solution needs to both access it and stay in contact for long enough to leach the valuable minerals. You need to drill some holes first, make some space to allow for rock expansion and permeability increase, and then break down or fracture the rock. The most difficult questions are how much money do you want to spend in fracturing the rock and how much recovery are you willing to potentially lose? Those questions will be unique for each ore body, and a lot of tests have to be conducted in advance to determine the most economical solution.

CIM: So drilling and blasting are two separate steps in this process?

Hiam-Galvez: Yes. There are many techniques in development, but from our experience, the most practical is directional drilling and confined blasting. Directional drilling was developed for the oil industry, so you can drill and go in any direction. Drilling gets you to the rock, but now you have to fragment it, and we have found that blasting works well and it is already commercially available. So to do this, you have to design how many holes you want to make, and how you are going to blast the rock.

CIM: What has the public response been to the in-situ mining approach?

Hiam-Galvez: Actually, the biggest obstacle right now is public perception that chemicals might leach out and appear somewhere else. We have technologies these days to monitor and provide proper containment of the solutions.

CIM: Once the valuable minerals are liberated and brought to the surface, what happens then? Is there a lot of waste generated?

Hiam-Galvez: The valuable metals are extracted using conventional technologies such as solvent extraction and electrowinning for copper or carbon columns for gold.

CIM: Tell me about the pilot test you just completed for ISR of copper sulfides in Poland.

Hiam-Galvez: I’ve been overseeing a big strategic project with EU funding with 21 companies participating where we demonstrated bioleaching and ISR for copper sulfides for a KGHM mine in Poland. Our goal was to prove the concept of deep bioleaching of copper sulfide. It also involved the design and engineering of the pilot reactor to make it work. Hatch designed the reactor to work in a mine 1,000 metres deep. We built it, operated it, trained the operators and ran it for months.

CIM: Does Canada have ore bodies that are amenable to ISR techniques in the future?

Hiam-Galvez: We have a few potential ore bodies in Canada, and Hatch is well positioned to help clients take ISR technology from the laboratory to commercial scale and make it work. Our whole team is based in Canada!

CIM: In 20 years, where will we be with ISR?

Hiam-Galvez: This approach is not for all ore bodies, but in 20 years I believe there will be commercial-scale applications in operation. Within five years, we’ll see ISR applications for copper oxides, which have more natural fractures, so it’s easier. Maybe even in the next two years.