The technical transformation practice in copper mineral processing plant in recent years was mainly introduced, And the successful experience was summed up so as to be used for spot produce.

介绍近年来铜选厂的技改实践，总结成功经验，供现场生产借鉴。

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This paper discusses the source of heat for spot welding and the theory of diffusion welding of brass and red copper.

探讨了点焊热量的来源和黄铜与紫铜的扩散焊机理。

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Spot welding procedure of copper with inlaid filler metal sheet HL204 is introduced, too.

介绍了铜与铜镶嵌片状钎料HL204点焊的工艺方法。

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Just as telling, the premium for spot copper over the nearest forward contract jumps up when buyers worry about being able to get their hands on the stuff.

ECONOMIST: Buttonwood

Commodities like oil, copper and iron ore just relapsed and both metallurgical and steam coal spot prices stick in the dumps despite serious cutbacks in production, worldwide.

FORBES: White Swans Beat Up On Black Swans

Citigroup estimates that the spot price is below the production costs for 15% of copper producers, 25% of aluminium producers, 50% of zinc producers, 30% of nickel producers and 10% of iron-ore producers.

ECONOMIST: Fortunes in the mining business come and go faster than ever