Abstract: The invention relates to a dynamically addressable slave unit, comprising a bus interface, an enable circuit having a switch and two control ports which are connected via the enable circuit. The enable circuit only releases the slave unit for assigning an address by an address signal provided at the bus interface when a control signal is provided at one of the control ports and when the switch of the release signal is open. Otherwise, the enable circuit locks the slave unit for the assigning of an address. The switch locks depending on whether a switching signal is provided at the bust interface directed to the address assigned to the slave unit. The invention further relates to a master unit for use with one or more dynamically addressable slave units, to slave units according to the invention, and to a method for dynamically addressing slave units according to the invention.

Abstract: The invention relates to a dynamically addressable slave unit, comprising a bus interface, an enable circuit having a switch and two control ports which are connected via the enable circuit. The enable circuit only releases the slave unit for assigning an address by an address signal provided at the bus interface when a control signal is provided at one of the control ports and when the switch of the release signal is open. Otherwise, the enable circuit locks the slave unit for the assigning of an address. The switch locks depending on whether a switching signal is provided at the bust interface directed to the address assigned to the slave unit. The invention further relates to a master unit for use with one or more dynamically addressable slave units, to slave units according to the invention, and to a method for dynamically addressing slave units according to the invention.

Abstract: A process for the preparation of titanium dioxide by the sulphate process in which titanium raw materials are decomposed with sulphuric acid, the resulting titanyl sulphate is hydrolyzed, the waste acid is separated from the hydrolyzate and evaporated to a concentration of 60 to 70%, sulphuric acid is separated from the solid metal sulphates, and the sulphuric acid which has been concentrated by evaporation is used again for the decomposition of the titanium raw material, the improvement wherein the 60 to 70% sulphuric acid is concentrated to 70 to 80% H.sub.2 SO.sub.4 in a further evaporation stage and the concentration of a part of this sulphuric acid is raised to a concentration of 98 to 99% H.sub.2 SO.sub.4 by the absorption of SO.sub.3 and then used together with the remainder of the above-mentioned 70 to 80% sulphuric acid for the decomposition of titanium raw materials.

Abstract: The invention pertains to a control circuit for a collectorless DC motor where at least one power transistor (14, 16) is input-connected to each stator coil (2, 4) of the motor; said transistor is driven by at least one rotor position sensor, especially a Hall generator having commutation circuits to commute the motor current, and where a blocking protection device is provided to interrupt the motor current in an overload or blockage. The blocking protection device (26) has at least one semiconductor circuit (30) carrying the motor current which is switched through or blocked depending on its temperature.

Abstract: Method and apparatus for driving an alternating-current motor. A sinusoidal supply AC voltage is rectified into a pulsating, unsmoothed DC voltage, with sinusoidal half waves and from this DC voltage an alternating-current motor voltage is produced by means of controllable polarity reversal. The pulse width of this alternating-voltage of the motor can be modulated. The polarity reversal takes place in accordance with the supply frequency in such a way that the AC voltage of the motor is essentially composed of the sinusoidal half waves of the pulsating DC voltage. For this purpose, the motor speed can be altered by changing the AC voltage of the motor with a constant timing frequency, lying outside the range of audibility, into pulse-width modulatable voltage pulses.

Abstract: Energy required for the calcining or drying operations in the production of titanium dioxide by the sulfate process and the chloride process is at least in part provided by burning by-product offgases containing carbon monoxide obtained in the chlorination of titanium-containing raw materials under reducing conditions.

Abstract: In the production of nitrobenzene by subjecting benzene to nitration with a mixture of nitric acid and sulfuric acid, separating off the nitrobenzene formed, concentrating the sulfuric acid by evaporation and returning the concentrated sulfuric acid to the bezene nitration stage, the improvement which comprises concentrating sulfuric acid to a concentration of from 75 to 92% by evaporation in vacuo at temperatures in the range from 130.degree. to 195.degree. C. Thereby the energy per kg of water evaporated is drastically reduced compared to processes wherein the sulfuric acid is concentrated to a higher level, without a corresponding loss in efficiency or capacity.

Abstract: An improved process for the preparation of TiCl.sub.4 comprising(a) chlorinating a raw material containing titanium and vanadium impurities to produce a crude TiCl.sub.4 reaction product,(b) separating the crude reaction product into solid by-products and TiCl.sub.4 -containing liquid,(c) reacting the TiCl.sub.4 -containing liquid with a reducing agent whereby vanadium impurities are converted into solid compounds, and(d) separating TiCl.sub.4 from the solid vanadium compounds, is improved by adding solid products of the vanadium reduction reactions to the crude TiCl.sub.4 reaction product prior to the separating step (b).

Abstract: In the desulphurizing of SO.sub.2 - and hydrogen halide-containing flue gases by catalytically oxidizing the sulphur dioxide on moist active carbon at a temperature of from 45.degree. to 70.degree. C. with the formation of 3 to 20% dilute sulphuric acid, the improvement which comprises contacting the dilute sulphuric acid with the hot flue gases to be desulphurized so as to evaporate water resulting sulphuric acid of a concentration of from 60 to 85%, and removing by evaporation the hydrogen chloride and hydrogen fluoride dissolved in the dilute sulphuric acid. Advantageously evaporation is carried out in two scrubbing stages, the hydrogen chloride and hydrogen fluoride being removed, by vacuum evaporation or by stripping with air or flue gas, from a mixture of the dilute sulphuric acid from the second scrubbing stage with the concentrated sulphuric acid from the first scrubbing stage, the mixture having the H.sub.2 SO.sub.4 concentration of from 40 to 70%.

Abstract: The invention procides a circulation evaporator for concentrating mineral acid, particularly sulphuric acid, comprising parts of, or at least coated with, enamel, characterized by a heat exchanger for heating the acid comprising at least one acid feed pipe provided with an enamel layer, means being provided to maintain the compressive stress in the enamel layer under all working conditions, said acid feed pipe being connected at its inlet end to a circulation pump and at its outlet end to a flash evaporator for concentrating the heated acid, this evaporator being connected by a circulation pipe to the pump inlet and to means for introducing the crude acid, for discharging the concentrate and for carrying away the vapors.

Abstract: A metallic iron-containing starting material such as iron filings, iron powder or a reduced ore such as ilmenite is oxidized with air in the presence of 5 to 40% of iron oxide and/or iron oxide hydroxide nuclei and about 2.5 to 200% of an electrolyte, percentages being based on metallic iron by weight. The oxidation is effected in aqueous suspension at 75.degree. to 100.degree. C and a pH of 4 to 6.5. If the nuclei are magnetite-free, at least the first quarter of the oxidation should be at pH 5 to 6.5. Preferred electrolytes are transition metal salts. The pigments are more intense in color and have a more pronounced blue tinge.