HOISTING
- Material bags are hoisted at the ZK Shaft or transported from the Southwell Adit.
- The bags are stored in a designated area within the ZK Shaft security fencing.
WEIGHING
- The bags will be weighed by VTN personnel in the presence of a Sheba Mineral Resources representative or a security official. Each bag will then be tipped into a separate bin above the ZK plant belt.
- The mass of the bags will be determined using a scale certified and calibrated by the supplier.
- The VTN recording clerk, under scrutiny from the Mineral Resources representative or security official, will record the individual bag mass on a daily log-sheet. The Mineral Resources representative or security official will countersign the completed log-sheet, which will be checked and signed by the mine Geologist after comparison with the weightometer reading.
- Once a quarter the Sheba, Consort and Fairview scales will weigh a designated bag and the readings for the same bag will be compared.
SAMPLING
- During the shift an appointed person from the Mineral Resources department will supervise the falling stream sampling when the container bin is emptied onto the ZK belt.
- When the belt is started the shaft bin empties onto the conveyor belt. A sliding tray is then pushed through the falling stream three times per belt length of ore. When the bin door is opened the rock falls onto the moving conveyor belt. The bin door is closed when a worker at the top of the belt signals that the total belt length is full of rock. During one belt run, three trays of sampled rock are emptied into the crusher. Big rocks that cannot go into the crusher is put aside and broken with a hammer, before being crushed. The crusher is set to obtain a minus 30mm sample. The crushed rock then empties into a riffler below the crusher. The crushed material is repeatedly passed through the riffler until two (approx. 5kg) samples can be collected. Both sample bags are tagged, one to be submitted for assay and the other to be kept in a secure location for two weeks as a reference.
The conveyor belt has a 1,8 ton holding capacity, thus a sample is taken for every 1,8 tons of rock entering the plant. After the sample is collected the belt is restarted to enable sampling of the next batch. The same procedure is followed for the next belt run, until the shaft bin is empty.
SAMPLING
- All the sealed samples representing the day’s production will then be submitted to security and transported using the normal mine procedures, to Performance Lab for assay.
- The daily-allocated grade will be the average of all the samples.
PERFORMANCE LAB PROCEDURE – ON RECEIPT OF THE DAILY COMPOSITE SAMPLES:
- The sample will be assayed for gold (2 x 25 gram).
The following methodology will be used for each sample:
- The sample will be crushed to 3mm and split through a Jones Riffler into four samples.
- An A and B sample will be milled (Pulverized) and then assayed for gold grade.
- If there is a greater than 20% discrepancy between the values obtained for A and B, then a third assay will be done using the C sample
- The rest of the sample material will be kept at Performance Lab for reference purposes for one week after the assay reporting date.
ACCOUNTING PROCEDURE
The Plant Superintendent and Geologist will be responsible for gold allocation.
- The assay results will be made available to the Geologist as soon as they are available.
- If the average value exceeds 100 g/t then the value is capped to 100 g/t for that sample.
- A moisture content of 2.5% will be assumed for the VTN material.
- The results of the samples will then be used to do the accounting for that particular day, adjusting the gold content according to grade, moisture content and daily plant recoveries.
- The assay results will be available to VTN daily and also be recorded on the daily production sheet.
- The daily summary sheet is to be posted daily, or as sample data is updated, on the “Production file” on the BML Server.
The Geologist and a representative of VTN mining will reconcile weekly to make sure that the accounting is done correctly and that both parties agree to the assay results.
At the end of each production month the gold to be allocated will be adjusted by:
- The overall on mine Plant Recovery and the BIOX® recovery.
- A gold allocation certificate signed by the Geologist, Plant Superintendent and VTN will be submitted to the Financial Manager to calculate payment.
PROCESS OF IMPLEMENTATION OF SOP’S
Once this Standard Operating Procedure has been finally accepted and signed off, it will be:
- A copy will be forwarded to the responsible HOD(s) for the specific area of operation;
- The HOD(s) will communicate this SOP to his/her subordinates while documenting the attendance. Should any person be absent for whatever reason, the responsibility remains with the HOD(s) to ensure that observers will be briefed at a later stage;
- This SOP will also be circulated to the Training Centre to ensure that training offered and Competency Assessments be adhered to accordingly; and
- A copy will be circulated to the Safety Department to review current Safety Inspections to accommodate the changes (if any).