The concept of the differential and cut-off grade is pointed out, and its mathematical model is built as well.
提出了级差边际品位的概念，建立了级差边际品位的数学模型。
They are respectively named cut-off grade, marginal grade, economic grade and the average grade of an ore deposit.
这4项品位指标依次为边界品位、边际品位、经济品位和矿床平均品位。
Cut-off grade method has been used to control the ore drawing in non-pillar sublevel caving mining both in and outside China.
采用无底柱分段崩落采矿法，国内外一直采用截止品位放矿法来控制出矿。
It is concluded that location of foot-wall drawing points are closely related to orebody dip, cut-off grade and ore grade of wall rock.
认为下盘放矿点位置与矿体倾角、放矿截止品位、围岩含矿品位有着密切的关系。
The greatest height of footwall cutting is determined through the theoretical analysis of cut-off grade method and breakeven point method.
通过对边界品位法及盈亏平衡法的理论分析，确定下盘最大切岩高度。
Research shows that main cause of ore dilution in sublevel caving mining is tlnrational cut-off grade drawing. Non-dilution ore drawing is most ideal drawing mede.
研究表明，造成无底柱分段崩落法来出矿石贫比大的根本原因在于采用了不合理的截止品位放矿方式，无贫化放矿是无底柱分段崩落法最为理想的放矿方式。
When dilutionless drawing cann't be executed in one step, low dilution drawing can be used and the cut-off grade can be gradually raised towards dilutionless drawing.
当不能一步到位地施行无贫化放矿时，可用低贫化放矿，逐渐提高截止品位而趋向无贫化放矿。
Optical grade with UV cut-off up to 400 nm, greater optical purity than standard grades.
光学级紫外截止到400纳米，大于标准等级的光学纯度。
Optical grade with UV cut-off up to 400 nm, greater optical purity than standard grades.
光学级紫外截止到400纳米，大于标准等级的光学纯度。
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