The main objective of ORE Quality Control is to ensure that ORE is mined according to the data, according to the mine plan, and according to customer needs. In essence, ORE Quality Control's main responsibilities are :

1. Minimizing the ORE wasted in disposal as waste
2. Minimizing OB, the waste that is also mined as ORE (as dilution material)

ORE Quality Control is absolutely necessary and an integral part of the nickel mining process, this is due to the variability of nickel ORE, both vertically and horizontally, which is very diverse and irregular. In the distribution of ORE, for certain areas it is shifted both horizontally and vertically as far as 2-3 meters, the material/content of nickel ORE can be very different.

Therefore, with the support of ORE control, which conducts sampling before, during, and after mining intensively with best practice method and obtains information on Ni% and Fe% levels in just 1-2 hours, is very helpful in determining whether the material in front of the excavator bucket is ORE or OB, so that the sampling result act like an eye in the mining process so that it is authentic.

This ORE quality control operation requires the support of a satellite laboratory (MRAL - Mine Rush Assays Laboratory) in the field which can support the results of the assays analysis for only 1-2 hours.

In its work, an outline is as follows :
(Image : The variability of nickel ORE, both vertically and horizontally)

1. ORE Quality Control leader is involved in weekly mining planning, meaning how many tonnes, Ni% and Fe% and other chemistr y specification that required, mined from which mine face, and will there be ORE blending of 2, or 3, or 4 mine faces that will be stacked in the cone of stockpile.
2. Then ensure that the number of samplers both in the mine face to monitor stripping, ORE exposure, mining, and even if the stockpile is sufficient.
3. Provide procedurer sampling that adjusted to ORE characteristic & best practise experience.
4. Arrange for efficient sample delivery from the mine face and stockpile to the MRAL lab
5. Ensure preparators and analysts are ready to work on the MRAL follow the standard laboratorium procedure, and ensure the X-ray reader is properly calibrated.
6. Ensure the sample numbering and communication systems are organized, so that information can be quickly and accurately returned from the Lab to the sampler in the mine faces in the field to direct the excavator whether mining or still stripping.

The illustration shows how ORE variability horizontally in the transition area between OB and ORE, as well as the transition of ORE and Bluezone. That is why we need the extra attention and sampling system to ensure no ORE wasted as OB.

It should be noted that the characteristic of nickel as an ORE are very different from coal. As nickel ORE does not have visual boundaries between the ORE and OB. No matter how much experience people have on dealing with ORE control, we need to the result of sample analysis from MRAL, because the color of the ORE when it’s dry, or wet, or day, or night will be different according to their location. This characteristic is very contrasting to coal that are visually can be differentiated.

To ensure the ORE quality or mineral in the mine is according to the needs of client that's why the strategy of ORE blending and stockpiling has a significant role.

This is related to the condition of ORE production more than 50,000 in a month would require mining activity in more than one mine face, that’s why the ORE from one mine face would be mixed with the second mine face in the provided stockpile. Or even more complex, it would be mixed with the third or fourth mine face.

Of course, in every mine face statistically contains different chemical characteristic. While the client will only provide the specification of Ni% and Fe% and other chemical substance. In that sense, the need to strategize the mining operation between one mine face to the other to produce the right number of ORE is high. How do we mix it? What do we mix?

In conclusion, we need to know the content of Ni% and other chemical substance from the ORE in the stockpile both fraction -1 ", fraction +1" -6 ", and fraction +6“ or both soft and rock materia.

There are few blending strategy that we can use, as follows :
(Image : ORE Blending on stockpile)

1. Blending Pit, which is the mixing of ORE in a mine face that is paired or mined together with other mine faces so that the pile of ORE in the stockpile is in accordance with the Ni% target and has defined characteristics.
2. Blending on stockpile is the process of mixing ORE between cone 1 and other cones in stockpiles because different characteristic ORE during mined from Pit. So that when it is transported to the ship, the ORE can be mixed based on calculation and according to customer requirements. In this blending on stockpile strategy, stock is usually carried out for materials with extreme chemical content such as high Fe or low Fe piles, or high Ni% pile and low Ni% stack so that the ingredients can be mixed as needed.

The very important thing needs to be done in this ore blending, that for each heap of ORE in the stockpile, for example one pile or one cone is 1000 tons, then sampling per truck when stacking is carried out so that we get the results of what is the Ni% content and the chemical specs of the ORE content in one pile of it. This will greatly determine the next step, whether per stack can be shipped directly because it is according to specifications or still needs to be mixed with high or low chemical content or even mixed between certain piles so that the time on the ORE ship has met the Ni% content, and the chemical specs requested client.

ORE modeling is an approach to spread of reserve according to the previous drilling data. Inverse distance method, nearest neighbour, and other methods can be used according to the geological characteristic and existing data. Replacement calculation is generally done by multiplying the volume of the block model or polygon method with the data density that we gain from test-pit. The assumption and boundaries with the replacement calculation are the minimum thickness of the ORE, standard cut of grade, data density, and mine-ability.

The points above will be used as the base for mine design, in which design access to mine, slope and production plan. This will be compared with the actual mining result, the quantity of OB and ORE, and how much the volume increased or decreased in the pit with calculating trough the topographic survey in certain period.

This comparison figure, or what we know as the reconciliation rate, will be a factor in further mine planning. This can be done on the condition that mining supported by ORE control is successful.