Abstract: An improved key telephone system realizes substantial reduction in installation costs, permits use of relatively small central units, provides compatability with telephone apparatus speaker phones, automatic dialers, etc., and provides additional advantages.

Abstract: A modulation system for use in analog signal transmission processes input information in multiple analog communication channels, for multiplexing onto a data channel. The system includes:A delta modulator and logic circuitry connected therewith to suppress data transmission when the modulator produces alternating 1's and 0's and to signal activation of pulse transmission when a successive sequence of at least two 1's and two 0's is transmitted by the modulator.

Abstract: A fixed center extruder die assembly is disclosed which serves to apply concentric layers of coating materials on an advancing core wire. The assembly which includes three concentrically arranged and interconnected components comprises an outer die block having a centered first passage with a first axis therethrough; a guiding die with a cylindrical tubing top concentrically disposed with the first passage and second passage therethrough with an axis coincident to the first; and an inner guide having a cylindrical tubing tip and thread passage therethrough which has an axis substantially coincident to the first axis. An improved hand tool is envisioned.

Abstract: The process of sulfidizing an acid copper leach pulp prior to flotation recovery of the copper therein comprising adding to and admixing with said pulp in a reaction zone an ionizable sulfide material, said sulfide material being added in an amount proportional to the amount of copper passing through said zone so that the sulfidization reaction is completed within about 30 seconds and the pulp leaving said zone has an aqueous copper concentration of from about 0.014 to 0.024 gram per liter and a reactor for such process comprising elongated tubular means, shaft means mounted in said tubular means, and a plurality of blade members attached to said shaft, said blade members being spaced along said shaft at approximately 30.degree. pitch angles relative to the axial direction of the shaft and there being a reverse pitch direction of certain of said blades at predetermined distances along the length of said shaft.

Abstract: A process for the recovery of metals from copper reverberatory slag containing iron in the form of silicates comprising roasting said slag in an oxidizing atmosphere at a temperature of at least about 550.degree. C in the presence of sulfur trioxide for a time sufficient to effect decomposition of substantially all of said iron present in the slag to iron oxide and the other metals therein to water-soluble salts and metal oxides, and separating the water-soluble metal salts and metal oxides from the iron oxide and silica residue.

Abstract: A switch assembly connectible to a circuit board comprisesA. an insulative strip containing first, second and third openings spaced apart in a row,B. two electrically conductive metallic prongs respectively extending through the strip via the first and third openings, andC. a fastener having a threaded shank extending into the strip via the second opening and having an electrically conductive head adapted to engage or disengage both prongs at one side of the strip depending on the extent of rotation of the shank relative to the strip.

Abstract: Copper, zinc and nickel are recovered from sulfide concentrates prepared from ores of one or more such metals by subjecting such concentrate to a leaching operation which comprises slurrying the concentrate in an aqueous solution containing ammonium sulfate and free ammonia and vigorously agitating the slurry at 50 to 80.degree. C. and below 10 psig. in the presence of free oxygen while vigorously recirculating said oxygen from above the surface of the slurry to a substantial depth below such surface. The resulting pregnant leach solution contains copper, zinc, and/or nickel in dissolved form complexed with ammonia and such solution is treated to recover the dissolved metal. The undissolved sulfidic residue from the leaching operation is subjected to a secondary flotation operation to produce a sulfide concentrate containing the metal values not dissolved in the leaching operation, and such concentrate is treated to recover such values, as by smelting or by releaching.

Abstract: An out-of-band signaling method and apparatus are provided to facilitate the adaptation of payphones to telephone systems, as for example subscriber carrier systems. Part of the speech band is made unavailable to the subscribers and is employed for signaling DC line conditions from one end of the telephone system to the other.

Abstract: An apparatus and method particularly adapted for use in preventing accumulation of material on at least a portion of a monitoring device for a foam scrubber or the like. The foam scrubber apparatus comprises a container having a layer of foam material therein, the improvement comprising monitoring means for monitoring said foam material, said monitoring means comprising a first means connected to the container, a second means centrally mounted in said first means, and extending into said foam layer, and fluid supply means in fluid-flow communication with a passage in said first means for supplying a stream of fluid into said first means through said passage and through said first means around said second means to prevent foreign material from accumulating on said second means.

Abstract: The process of sulfidizing an acid copper leach pulp prior to flotation recovery of the copper therein comprising adding to and admixing with said pulp in a reaction zone an ionizable sulfide material, said sulfide material being added in an amount proportional to the amount of copper passing through said zone so that the sulfidization reaction is completed within about 30 seconds and the pulp leaving said zone has an aqueous copper concentration of from about 0.014 to 0.024 gram per liter and a reactor for such process comprising elongated tubular means, shaft means mounted in said tubular means, and a plurality of blade members attached to said shaft, said blade members being spaced along said shaft at approximately 30.degree. pitch angles relative to the axial direction of the shaft and there being a reverse pitch direction of a certain of said blades at predetermined distances along the length of said shaft.

Abstract: An improved apparatus and method for separating gaseous pollutants and particles from a gas with a foam layer wherein the apparatus includes means for monitoring the foam layer composition and/or height of the foam layer, dispensing means for dispensing a liquid to said foam layer, and means responsive to said monitoring means for activating said dispensing means to control the dispensing of liquid through the dispensing means. The method comprises the steps of monitoring the pressure drop and/or height of the foam layer and dispensing a liquid to the foam layer, when its composition and/or thickness varies beyond a predetermined point, for a time sufficient to bring the composition and/or level of the foam layer back to said predetermined point.

Abstract: An active filter comprises:A. a transmission line and a common, the line having an input side and an output side,B. first and second parallel paths each connected between the transmission line and the common, each path including series connected resistance and capacitance elements, andC. at least two amplifiers associated with each path, each amplifier having input and output terminals connected with different points along said path.

Abstract: An improved process particularly adapted for cleaning dry particulate matter of a catalyst filter bed without requiring the removal, screening and reinstating of such material forming the catalyst filter bed.

Abstract: A ferrite inductor is coated with fluorocarbon particles prior to attachment to a printed circuit board.

Abstract: A telephone system comprises a plurality of station sets, each including a plurality of key buttons, and the system includesA. a station circuit for at least one of the station sets, said station circuit including interface means for transferring data to and receiving data from its associated station set, said interface means including between 2 and 3 pairs of wires connected with the station set, one pair of which is a talk pair, and the remainder of which is or are for power transmission and for transmission of data related to line, status and audible signalling and for control information including switch status, andB. a line circuit for at least one line, each line circuit including means for transmitting control, status and talk information to, and receiving control, status and talk information from, at least one station circuit connected therewith.

Abstract: In a high-frequency communication cable with foam plastic insulation and an outer conducting tape having a bonded longitudinal overlapped seam, a separate metal bridging strip is inserted under the seam.

Abstract: A process is described for the selective recovery of aluminum from an impure solution in which aluminum is dissolved, comprising contacting said solution with a symmetrical bis(3,5-C.sub.1 -C.sub.10 alkyl-substituted phenyl) hydrogen phosphate to extract the aluminum, and separating the aluminum from said extract.

Abstract: A bridge circuit for measuring the D.C. resistance of a resistive element having an induced A.C. current comprises impedance legs whereby the A.C. component can be balanced out. The invention has particular application to the measurement of high-voltage cable conductor temperatures.

Abstract: A method and apparatus which are particularly adapted for use in the selective and coordinated abstracting of samples to be examined. Essentially, the selector apparatus which has a support means may embody delivery means, receiving means, collection means, and control means. In a preferred embodiment, the receiving means is operatively connected to the support means and includes a plurality of receptacles for receiving flowable material. The delivery means is supported by the support means and may include at least one, but, desirably a plurality of, movable delivery members which carry flowable material therethrough. Each delivery member is selectively movable between a first position and a second position.

Abstract: Lead is recovered from lead sulfide concentrates or mixed lead-zinc concentrates containing iron sulfide by forming a slurry of such concentrates in an aqueous medium containing ammonium sulfate and free ammonia, and introducing such slurry into a closed reaction vessel at a pressure not exceeding 30 psig. Oxygen also is introduced into such vessel to establish therein a partial oxygen pressure of at least a few psi, while vigorously agitating the slurry. The lead sulfide content of the concentrates thereby is converted to the form of substantially water-insoluble oxidic lead compounds, while any zinc sulfide present is dissolved. The slurry then is withdrawn from the reaction vessel and the insoluble residue is separated from the aqueous solution. The latter is treated for recovery of its zinc and ammonia content, and the residue is subjected to a froth flotation operation to form a concentrate containing substantially all the iron sulfide and a tailing containing the oxidic lead compounds.