CAMECO CORP

Mining methods

At Cigar Lake, the permeable sandstone that overlays the deposit and basement rocks, contains large volumes of water at significant pressure. Before we begin mining, we freeze the ore zone and surrounding ground. We use a JBS to mine the ore.

Artificial ground freezing (AGF)

The current method of mining the Cigar Lake orebody uses progressive block freezing of portions of the mineralized zone and adjacent host rock. Freezing the orebody reduces the risk of potential inflow of groundwater and release of radon gas into the workplace, while increasing cavity stability and standup time during mining. The freezing strategy is to bulk freeze the ore zone and the surrounding area prior to start of mining in a given area. Frozen cavity criteria are applied to each cavity prior to mining to ensure it meets the minimum standard prior to excavation.

This AGF system freezes the deposit and surrounding rock to between-5°C and-25°C in two to four years, depending on freeze pipe geometry and ground properties such as water content and thermal conductivity.

JBS mining

As a result of the unique geological conditions at Cigar Lake, we are unable to utilize traditional mining methods that require access above the ore, which necessitated the development of anon-entry mining method specifically adapted for this deposit. After many years of test mining, we selected jet boring, anon-entry mining method, and it has been used since we began mining in 2014. This method involves:

This is anon-entry method, which means mining is carried out from headings in the basement rock below the deposit, so workers are not exposed to the ore. This mining approach is highly effective at managing worker exposure to radiation levels. Combined with ground freezing and the cuttings collection and hydraulic conveyance system, jet boring reduces radiation exposure to acceptable levels that are below regulatory limits.

The mine equipment fleet is currently comprised of three JBS units plus other equipment to support mine development, drilling and other services. Additional scooptrams, plus some smaller ancillary equipment, will be added to the current equipment fleet to meet the production and development requirements for the remainder of the mine life.

We have divided the orebody into production panels. At least three production panels need to be frozen at one time to achieve the full annual production rate of 18 million pounds. One JBS machine will be located below each frozen panel and the three JBS machines required are currently in operation. Two machines can actively mine at any given time while the third is moving, setting up, backfilling or undergoing maintenance.