It is the cheapest and most economicalgrade of nests.
价格便宜，也是最经济的品种。
2
Based on the technical and economical index, an optimal decision for the cutoff grade of ore drawing is presented.
在获取矿石技术经济指标的基础上，对截止放矿品位进行了优选政策。
3
Precision of reserves, grade and spatial distributing is the base of economical appraise, research of feasibility, programming of mine and optimize exploitation.