East African gold producer Caracal Gold has announced the discovery of a new high-grade zone above the current underground workings and above the areas drilled as part of the mineral resource estimate (MRE) on the Kilimapesa Hill deposit, in Kenya. 

This comes in addition to the more than 1.3-million ounces of Joint Ore Reserves Committee-compliant gold resources that the company already controls. 

"The Caracal and Kilimapesa exploration teams have always believed that significant high-grade zones exist within the Kilimapesa Hill deposit. As we open and expand the opencast mining pits, to support the expansion project, we expect to find more of these zones. The potential size of this high-grade zone is encouraging,” Caracal CEO Robbie McCrae said on March 21. 

The discovery is estimated to allow for about 360 t/d of high-grade material, with average grades from 3.31 g/t to 4.74 g/t, to be processed. A mining plan confirming 90 days of high-grade material has been prepared and is being actioned, with exploration to define the full potential of the high-grade zone underway.  

The area is currently being accessed from the current openpit, and with exploration drilling on hold at present, a decision was made to bulk sample the area and process the material through the milling plant. 

Mining began on the zone on March 9, and 360 t/d is being processed through the milling plant. Current recoveries are 75% and plant availability over 85%. 

Currently, six zones have been mapped and sampled and had bulk samples processed. These zones are numbered 1A, 1B, 2A, 2B, 3A and 3B. Each of these areas has been intensively sampled and the resulting information put into a mining plan which supports throughput of high-grade ore through the milling plant for the rest of March and for the second quarter of this year. 

Caracal said that the exploration team was now extending the work on the high-grade zone to define the full extent of the strike, and that this would be followed by trenching and sampling and ultimately drilling, with the goal of defining high-grade ore for long-term processing through the milling plant and including the ounces into the Kilimapesa Hill MRE.

Hourly belt cuts are taken on the mill feed conveyor and the daily summary sampling sheets for samples are attached. These samples are assayed in the Kilimapesa laboratory. The sampling and analytical procedures used by Caracal are subject to a comprehensive quality assurance and quality control (QAQC) programme, the company assured.  

The QAQC programme involves insertion of duplicate samples, blanks and certified reference materials in the sample stream. Gold analyses are performed by standard fire assaying protocols using a 50 g charge with atomic absorption finish and a gravimetric finish performed for assays greater than 10 g/t. 

“We have had a plan to expand the MRE on the Kilimapesa Hill deposit. The plan includes additional drilling along strike and at depth. The identification and extent of this high-grade zone now adds a third leg to the drilling strategy. The strategy also includes the optimisation and expansion of the current milling plant alongside the development of a 65 000 t/m heap leach facility, and these will get us to the 24 000 oz/y target,” McCrae said. 

He explained that, in the past, Caracal used to process up to 1 000 t/d to achieve target production of 1 000 oz a month. Now, with the increased grade and reduced throughput of 360 t/d, Caracal’s current production monthly is estimated to be 790 oz a month from the milling plant and 160 oz a month from the heap leach pilot plant.  

“These estimates will most likely improve as we have scope to increase tonnage, optimise recovery in the milling plant and the heap leach is expected to continue to improve. Caracal and Kilimapesa are bound to be in a strong operational and financial position as we progress the funding required for the Kilimapesa expansion project in the second quarter," McCrae said.