前言 1981年2月至1983年2月,笔者在加拿大不列颠哥伦比亚大学采选系进修期间,从事细粒砂金选矿的课题研究,了解到加拿大和美国此项技术进展的一些情况。其中,有些尚未书面发表,有些则仅见于发行较窄的期刊。这类资料,国内读者难以获得,应该加以介绍。鉴于其篇幅较大,故分成几个独立单元,分期刊载,以便于有关同志参考。 Preface From February 1981 to February 1983, the author engaged in the study of fine grained gold beneficiation during the study of the Department of Anthropology at the University of British Columbia in Canada, and got some information on the progress of this technology in Canada and the United States. Some of them are not yet published in writing, while others are only found in narrower periodicals. Such information, domestic readers difficult to obtain, it should be introduced. In view of its large space, it is divided into several independent units, which are published in phases so as to facilitate the reference of the comrades concerned.