Ore grade concept

(1) The concept of ore grade

Usually we refer to any element or mineral available in the ore as a useful ingredient. The amount of supplies in the ore contained in the ore is indicated.

The so-called grade is: the ratio of the weight of the useful ingredients in the ore to the weight of the ore, expressed as a percentage (%).

Grade = ore weight / weight of useful ingredients in ore × 100% (or g / ton)

Generally it refers to the percentage of metal grade of the metal elements in the ore.

For grades of precious metals (gold, platinum, etc.) ore, it is expressed in grams per ton. This is because these precious metals are rarely present in the ore.

(2) Boundary grade

This refers to the content and minimum limits of the useful components of the mineable stone. It is the lowest grade on the ore at the boundary of the ore body. It is the standard for dividing the ore and waste rock and delineating the ore body range. Within the scope of the delineated mine, the grade of any sampling point should generally not be less than the cut-off grade.

(3) Minimum industrial grade

It refers to the lowest value of the average grade that meets the requirements of industrial mining within the scope of the ore body defined by the boundary grade.

This means that according to the current level of industrial technology, when the grade of the ore is lower than a certain value, there is no value of utilization. The ore grade of this value is called the lowest industrial grade, or the mine is the mine with the boundary defined by the grade. The average grade of a block in a body or ore body must be higher than the minimum industrial grade to have a mining value, otherwise there is no mining value.

【note】
1 The cut-off grade and the lowest industrial grade are also relative concepts and can be varied.

2 Example of representation of grade:

Qijiang iron ore grade of greater than 30% hematite, Cen gold ore, magnetite grade 56.24%; Hui Tongshan copper grade of 2.04%, grade 3-5 Western Gold g / t gold grade of 15 g Qin Cen / ton, Honghuagou gold mine grade 14.46 g / ton (average).