VIDEO: Meet mining engineering grad student Fazl Jahromi

Posted on May 10, 2017

Queen's mining engineering graduate student Fazl Jahromi is exploring ways to make mine waste safer, less damaging to the environment, and less expensive to manage. It's all about arsenic immobilization and it's work that could one day save governments and companies billions.

Learn more about the Robert M. Buchan Department of Mining and read more about Jahromi's supervisor, Queen's engineering Professor Ahmad Ghahreman.

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    Video transcript:

    Hi my name is Fazl Jahromi and I'm working under the supervision of Dr Ahmad Ghahreman. My research is about copper mostly.

    As you know 70 percent of copper is in form of chalcopyrite and one of most major chalcopyrite contaminants is enargite. Enargite is one of the minerals contains about eight percent of arsenic in concentrate and it's a major concern for environmental issues. So, because enargite contains arsenic, it makes most of the processing methods unviable. We are trying to develop a process based on using activated carbon and hydrochloric acid which is good for the environment and also viable for industry.

    So, in this experiment I'm running here, we have some sort of reactor with heater jacket to keep the temperature up. One of the temperatures we are working on is mostly about 80 degrees C to 90 degrees C and is viable to apply in industry.And, we have a copper solution, as we can see the green-black colour is from the copper which is dissolved into the acid medium here.

    So, we have our activated carbon beads to help us to improve the process of leeching. These carbon beads help us to oxidize more and more of those minerals into the hydrochloric acid and we are also sparging oxygen to this reactor to improve the oxidation process.

    The medium of leeching is mostly hydrochloric acid with some ferric sulfate solution in it to improve the leeching. When we put enargite concentrate inside our solution, this enargite concentrate starts to dissolve in the presence of activated carbon and oxygen sparging. And the copper leeches into to the solution and makes this nice green colour here for us.

    With this method, we are separating all of the copper from the enargite material and also we dissolve all the arsenic and separate it from the gain. After that the arsenic precipitation is happening autonomously inside the solution and making a ferric arsenic, or scorodite which is very safe for the environment and can be safely dumped in the environment.

    The contamination decreases a lot with this kind of method and we recover all the copper from anargite. We reached about 99 percent of copper recovery after four days of operation, which is pretty good for us.

    When we dissolve arsenic into the solution, we need to change the arsenic three to arsenic five to be safer for the environment after the change in arsenic three to five, with the help of this activated carbon beads we precipitate out the arsenic in the form of scorodite, which is much safer for the environment So, when we have scorodite, it doesn't dissolve into the ground water system or come into the water table.

    This is exactly what we're getting out of the process which is the safe form or arsenic. We have already separated the copper in the solution and recovered the copper.