In all things to do with PEN, I defer to the more informed and...

In all things to do with PEN, I defer to the more informed and knowledgeable posters, but I tried to find the difference between ISL and ISR. This excerpt from http://www.world-nuclear.org/info/inf27.html helped, acid vs alkali leach.

In situ leaching (ISL), also known as solution mining, or in situ recovery (ISR) in North America, involves leaving the ore where it is in the ground, and recovering the minerals from it by dissolving them and pumping the pregnant solution to the surface where the minerals can be recovered. Consequently there is little surface disturbance and no tailings or waste rock generated. However, the orebody needs to be permeable to the liquids used, and located so that they do not contaminate ground water away from the orebody.

Uranium ISL uses the native groundwater in the orebody which is fortified with a complexing agent and in most cases an oxidant. It is then pumped through the underground orebody to recover the minerals in it by leaching. Once the pregnant solution is returned to the surface, the uranium is recovered in much the same way as in any other uranium plant (mill).

In Australian ISL mines (Beverley and the soon to be opened Honeymoon Mine) the oxidant used is hydrogen peroxide and the complexing agent sulfuric acid. Kazakh ISL mines generally do not employ an oxidant but use much higher acid concentrations in the circulating solutions. ISL mines in the USA use an alkali leach due to the presence of significant quantities of acid-consuming minerals such as gypsum and limestone in the host aquifers. Any more than a few percent carbonate minerals means that alkali leach must be used in preference to the more efficient acid leach



The Australian government has published a best practice guide for in situ leach mining of uranium, which is being revised to take account of international differences.

The link for the best practice guide is

http://www.ga.gov.au/minerals/research/national/advice/uranium-mining-draft-release.jsp

Cheers .. Mandi