目前，世界上约有70%的锌来自开采的矿石，30%来源于回收锌或二次锌。
At present, approximately 70% of the zinc produced worldwide originates from mined ores and 30% from recycled or secondary zinc.
发现了一些前人未曾揭示的规律，条采巷道闭合变形将出现两个极值，其距离大于普通开采巷道，因此，巷道应在前方峰值压力第二次采动影响时加强支护。
Some deformation features that have not been discovered before are found. There are two peaks of displacement in strip mining roadway, and their lag distance is longer.
露天矿边坡驻留矿体开采使边坡产生了第二次卸荷作用。
The recovery of the residual ore-body under the slope of the open-pit, easily results in the second unloading of the slope.
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