HOISTING BULK MATERIAL – Material is accumulated underground in designated ore passes and hoisted at a designated time as indicated by the MO and the shaft foreman.
WEIGHING BULK MATERIAL – A weightometer on the No.3 belt at the tunnel is used to measure the VTN tonnage. The Fairview shaft foreman is responsible to ensure that the tunnel silo is empty and to record the opening reading on the weightometer, before VTN material is tipped. The Fairview shaft foreman is also responsible to record the closing weightometer reading after the last of the VTN material has passed over it. These weightometer readings are also recorded into the sampling supervisor’s control book. At the end of every production month a comparison is made between the No.3 tunnel weightometer and the plant weightometer. Any stock movement during the month is also brought into account and a correction factor is applied to the tunnel weightometer This correction factor is then also applied to the final VTN tonnage for the month. This calculation is made available to VTN for their scrutiny and records. Until such time as accurate moisture content measurement can be carried out at the tunnel, an assumed moisture content of 2% will be used and applied to the final tonnage calculation.
SAMPLING BULK MATERIAL
Sampling of the VTN material is done after the ore has been crushed and is being loaded into the aerial cars. BML supplies a sampling supervisor and VTN the required personnel. A sampling scoop is used to collect ore from the falling stream as it is discharged into the aerial car. The following procedure is to be adhered to:
- The sampler at the discharge point will collect one sample scoop of falling ore for every 5th aerial car that is loaded.
- The sampled material is collected in a bucket for a total of five scoops.
- The collected material is then passed through a riffler and sealed into two tagged sample bags.
- The one bag will be submitted for assay and the other bag kept as a reference for a minimum of two weeks.
- The reference samples are to be stored in a secure location at the tunnel and the samples to be assayed are taken to the BIOX plant, together with a checklist, for collection the following morning for transport to the assay lab.
- The last sample in a batch could consist of less than five scoops. This must be indicated on the sample control sheet to enable correct weight for average grade calculation.
- Every completed sample must either be locked away or kept under constant surveillance.
HOISTING BAGS
- Material that is collected into bags are to be brought to surface according to existing shaft procedures. The bags are to be stored on surface until the material is weighed and crushed.
WEIGHING AND HANDLING OF BAGGED MATERIAL
When sufficient bagged material has been accumulated on surface, the bags are to be weighed before being discharged through the jaw crusher while the following procedure is adhered to:
- The scale must have an up to date certificate of accuracy.
- Each bag is weighed in the presence of a security person and signed off by that security person at the end of the batch.
- The crushed material is then accumulated in the storage bin.
- The weightometer reading on the No 1 belt is to be recorded before the sampling is initiated and after the sampled material has passed over the No 1 belt weightometer.
- This will serve as a check, but the weight of the bags will be used for gold accounting.
- Once a quarter a scale calibration test is to be performed by using the Sheba, Consort and Fairview scales to weigh the same bag.
SAMPLING OF BAGGED MATERIAL
Once the bagged material has been weighed and crushed, it is ready to be sampled. The following procedure is to be adhered to:
- Sampling is to be carried out where the feed belt from the storage bin discharges into the hopper.
- A clearly visible mark is to be painted on the feed belt.
- Every time this mark passes over the drive pulley, a shovel is to be passed through the falling stream and the accumulated material is passed through a riffler.
- This process is to be repeated ten times. The accumulated material is to be riffled again until a sample bag can be filled by each side of the riffler.
- The one bag will be submitted for assay and the other bag kept as a reference for a minimum of two weeks.
- The reference samples are to be stored in a secure location at the tunnel and the samples to be assayed are taken to the BIOX plant, together with a checklist, for collection the following morning for transport to the assay lab.
- The last sample in a batch could consist of less than ten scoops. This must be indicated on the sample control sheet to enable correct weight for average grade calculation.
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.
- 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 Chief Geologist or Chief Surveyor 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 git, then the value is capped to 100 gi t for that sample.
- A moisture content of 2% is to be assumed.
- The results of the samples will then be used to do the accounting for that particular day, adjusting the gold content according to grade and moisture content.
- The assay results will be available to VTN and also be recorded on the production sheet.
- 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 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 Manager Finance & Admin to calculate payment.