Abstract: In order to decrease arsenic, which is a harmful substance, in a copper concentrate, provided is a method for selectively recovering an arsenic-containing copper mineral from a mixture including the arsenic-containing copper mineral and a non-arsenic-containing copper mineral, and a flotation agent used in the same. For a collecting agent, which is a component of the flotation agent used in a flotation step for selectively recovering the arsenic-containing copper mineral from the mixture including the arsenic-containing copper mineral and the non-arsenic-containing copper mineral, a sulfide compound having an R1—S—R2 (in this expression, R1 is a C5-10 alkyl group, and R2 is a C1-10 alkyl group) structure such as methyl n-octyl sulfide or di-n-octyl sulfide is used.

Abstract: In a communication system comprising a two-wire bus, bidirectional communication is carried out in a time division multiple access fashion through the two-wire bus between a plurality of terminal equipments (26) coupled to the two-wire bus and a central terminator (24) connected to one end of the two-wire bus which has the other end terminated by an active terminator (25). The central terminator transmits, to the two-wire bus, a down burst comprising a down synchronization signal and a down information signal. Each terminal equipment establishes synchronization with reference to the down synchronization signal and thereafter receives the down information signal. The active terminator sends, towards the central terminator, only an up synchronization signal produced with reference to the down synchronization signal extracted from the down burst. Each terminal equipment transmits an up information signal towards the central terminator in the form of an up burst with reference to the up synchronization signal.