Abstract: The present invention contemplates treating a zinc sulfate containing solution, especially a neutral leach filtrate with a reducing agent selected from ZnSO.sub.3, SO.sub.2 or mixtures thereof to substantially reduce the oxidant therein and to obtain a solution having a predetermined pH. Thus, in one embodiment of the present invention, a neutral leach filtrate containing an oxidant selected from permanganate and manganate ions and mixtures thereof is treated with a reducing agent selected from ZnSO.sub.3, SO.sub.2 or mixtures thereof in amounts sufficient to substantially reduce all the manganese ions present (permanganate and/or manganate) to the divalent state and to provide a zinc sulfate solution for electrodeposition of the zinc having a predetermined pH.

Abstract: The present invention contemplates providing a finely divided copper calcine and thereafter subjecting the calcine to reduction flash smelting. Indeed, significant processing advantages are achieved by dead roasting a finely divided copper concentrate, especially in a fluid bed reduction zone, and thereafter subjecting the resulting calcine to reduction flash smelting. Gases from the dead roaster and the flash smelter are combined for SO.sub.2 recovery in an acid plant.

Abstract: The present invention is predicated upon the discovery that in the electrowinning of copper from solutions thereof, a hydrogen fed porous catalytic anode can be caused to operate under such conditions of constant current flow whereby a dynamic equilibrium will be imposed upon the hydrogen fed anode so that the anode will behave as a normal copper anode in a refining mode. This is particularly true when such a hydrogen fed anode is deactivated by copper buildup on the surface of the electrode.

Abstract: A channel selector system in a radio for sequentially selecting one of a plurality of channels and rapidly scanning through any restricted channels such that the restricted channels are not displayed and appear to be skipped. The radio includes a frequency synthesizer for generating a predetermined frequency associated with each selected channel and the channel selector system has a signal generator which causes the frequency synthesizer to sequentially either step or scan through the channels including some channels which may be restricted. The generator provides an output coded signal to indicate selection of a restricted channel which is decoded by decoding circuitry. A scan timer is responsive to the decoded signal to cause the signal generator to rapidly scan through restricted channels. A latching circuit latches a signal generator input during rapid scanning through restricted channels until the system advances to the next unrestricted channel. Related methods are disclosed.

Abstract: A remote control system and method therefor is disclosed that includes a control station coupled by a two-wire line to a base station having a transmitter for providing simplex radio communications to mobile radios. The control station utilizes digital pulsed DC signalling to select a radio channel of the base-station transmitter for transmission of each message. In response to activation of a transmission switch, the control station applies a DC voltage to the two-wire line and thereafter applies a command pulse train having a predetermined number of pulses corresponding to the selected radio channel. The base station is responsive to the DC voltage on the two-wire line for receiving the command pulse train. The pulses in the received command pulse train are totalized, and the base station transmits the message on the radio channel corresponding to the totalized number of pulses.

Abstract: A method is provided for extracting silver from a silver sulfate-bearing substance, such as oxide materials, metal or metal sulfate mixtures containing silver sulfate which comprises subjecting said substance to aqueous leaching to remove soluble salts therefrom and leave a residue, taking the residue containing silver sulfate and other insoluble materials, such as insoluble salts, and forming a slurry with an aqueous solution of a metal sulfate, such as calcium nitrate, the amount of calcium nitrate being at least sufficient to effect metathetical exchange with the silver sulfate and form a silver nitrate solution containing substantially the silver originally present in the silver-sulfate bearing substance, and separating the silver nitrate solution from the residue remaining, and then purifying said solution, the silver being thereafter recovered from the silver nitrate solution by hydrolytic precipitation, electrowinning or other suitable means.