A system for producing nitric acid at reduced power consumption including an air compressor, to provide in a compressed air stream; a source of pressurized oxygen-rich gas having a pressure higher than the pressure of the compressed air stream; a mixing apparatus for mixing the oxygen-rich gas/compressed air stream mixture with an ammonia gas stream; an ammonia converter, to provide in a NO.sub.x gas/steam mixture; a water cooler/condenser for separating and condensing steam from NO.sub.x gas in the gaseous NO.sub.x gas/steam mixture; a NO.sub.x gas compressor, for compressing the gaseous NO.sub.x stream; an absorption tower downstream the water cooler/condenser, to provide in a stream of raw nitric acid-containing residual NO.sub.x gas and a tail gas including NO.sub.x gases; a mechanism for splitting the tail gas into a first tail gas stream and a second tail gas stream; and a mechanism for adjusting the amount of tail gas being split.

Nanocrystalline metal powders comprising tungsten, molybdenum, rhenium or niobium can be synthesized using a combustion reaction. Methods for synthesizing the nanocrystalline metal powders are characterized by forming a combustion synthesis solution by dissolving in water an oxidizer, a fuel, and a base-soluble, ammonium precursor of tungsten, molybdenum, rhenium, or niobium in amounts that yield a soichiometric burn when combusted. The combustion synthesis solution is then heated to a temperature sufficient to substantially remove water and to initiate a self-sustaining combustion reaction. The resulting powder can be subsequently reduced to metal form by heating in a reducing gas environment.

A process and system are disclosed for producing a lithium product from a solution comprising lithium nitrate. The solution comprising lithium nitrate can be obtained by reacting a lithium-containing metal silicate with nitric acid. The process and system comprise subjecting the solution comprising lithium nitrate to a first thermal treatment procedure (in one or more heated vessels) in which water and nitric acid (when present) are removed, and whereby a resultant lithium nitrate-rich crystal slurry is heated to produce a molten liquid. The process and system also comprise passing the molten liquid to a second thermal treatment procedure (in a further-heated vessel) in which the molten liquid is heated to substantially decompose lithium nitrate to lithium oxide.

A process and system are disclosed for producing a lithium product from a solution comprising lithium nitrate. The solution comprising lithium nitrate can be obtained by reacting a lithium-containing metal silicate with nitric acid. The process and system comprise subjecting the solution comprising lithium nitrate to a first thermal treatment procedure (in one or more heated vessels) in which water and nitric acid (when present) are removed, and whereby a resultant lithium nitrate-rich crystal slurry is heated to produce a molten liquid. The process and system also comprise passing the molten liquid to a second thermal treatment procedure (in a further-heated vessel) in which the molten liquid is heated to substantially decompose lithium nitrate to lithium oxide.

The invention relates to a process and apparatus for preparing nitric acid by catalytic oxidation of NH.sub.3 by means of oxygen and subsequent reaction of the NO.sub.x formed with an absorption medium in an absorption tower, which comprises a catalyst bed for N.sub.2O decomposition arranged in the process gas downstream of the catalytic NH.sub.3 oxidation and upstream of the absorption tower in the flow direction and a catalyst bed for NO.sub.x reduction and effecting a further decrease in the amount of N.sub.2O arranged in the tailgas downstream of the absorption tower in the flow direction, wherein the amount of N.sub.2O removed in the catalyst bed for N.sub.2O removal arranged in the process gas is not more than that which results in an N.sub.2O content of >100 ppmv and a molar N.sub.2O/NO.sub.x ratio of >0.25 before entry of the tailgas into the catalyst bed for NO.sub.x reduction and the catalyst bed for NO.sub.x reduction and effecting a further decrease in the amount of N.sub.2O arranged in the tailgas contains at least one iron-loaded zeolite catalyst and NH.sub.3 is added to the tailgas before entry into the catalyst bed in such an amount that an NO.sub.x concentration of <40 ppmv results at the outlet from the catalyst bed and the operating parameters are selected in such a way that an N.sub.2O concentration of <200 ppmv results.

The invention relates to a process and apparatus for preparing nitric acid by catalytic oxidation of NH.sub.3 by means of oxygen and subsequent reaction of the NO.sub.x formed with an absorption medium in an absorption tower, which comprises a catalyst bed for N.sub.2O decomposition arranged in the process gas downstream of the catalytic NH.sub.3 oxidation and upstream of the absorption tower in the flow direction and a catalyst bed for NO.sub.x reduction and effecting a further decrease in the amount of N.sub.2O arranged in the tailgas downstream of the absorption tower in the flow direction, wherein the amount of N.sub.2O removed in the catalyst bed for N.sub.2O removal arranged in the process gas is not more than that which results in an N.sub.2O content of >100 ppmv and a molar N.sub.2O/NO.sub.x ratio of >0.25 before entry of the tailgas into the catalyst bed for NO.sub.x reduction and the catalyst bed for NO.sub.x reduction and effecting a further decrease in the amount of N.sub.2O arranged in the tailgas contains at least one iron-loaded zeolite catalyst and NH.sub.3 is added to the tailgas before entry into the catalyst bed in such an amount that an NO.sub.x concentration of <40 ppmv results at the outlet from the catalyst bed and the operating parameters are selected in such a way that an N.sub.2O concentration of <200 ppmv results.

An apparatus for starting up and/or shutting down a plant for preparing nitric acid from ammonia and oxygenous gas may include at least one air compressor, at least one process gas cooler, at least one feed water preheater, and at least one residual gas turbine. The at least one process gas cooler and the at least one feed water preheater may include pipe coils, at least one of which is connected to a source for a heating medium such that the at least one pipe coil in the process gas cooler and/or the feed water preheater can be charged during startup and/or shutdown of the apparatus with the heating medium for heating the process gas flowing through the process gas cooler and feed water preheater. The apparatus may further include a heat exchanger downstream of the process gas cooler and/or the feed water preheater for transferring thermal energy from the heated process gas to the residual gas supplied to the residual gas turbine. Corresponding methods are also disclosed.

An apparatus for starting up and/or shutting down a plant for preparing nitric acid from ammonia and oxygenous gas may include at least one air compressor, at least one process gas cooler, at least one feed water preheater, and at least one residual gas turbine. The at least one process gas cooler and the at least one feed water preheater may include pipe coils, at least one of which is connected to a source for a heating medium such that the at least one pipe coil in the process gas cooler and/or the feed water preheater can be charged during startup and/or shutdown of the apparatus with the heating medium for heating the process gas flowing through the process gas cooler and feed water preheater. The apparatus may further include a heat exchanger downstream of the process gas cooler and/or the feed water preheater for transferring thermal energy from the heated process gas to the residual gas supplied to the residual gas turbine. Corresponding methods are also disclosed.

A system for producing nitric acid at reduced power consumption, including an air compressor producing a compressed air stream; a source of pressurized oxygen-rich gas having a pressure higher than the pressure of the compressed air stream; a mixing apparatus for mixing the oxygen-rich gas/compressed air stream mixture with an ammonia gas stream; an ammonia converter to provide in a NO.sub.x gas/steam mixture; a water cooler/condenser for separating and condensing steam from NO.sub.x gas in the gaseous NO.sub.x gas/steam mixture; an absorption tower downstream the water cooler/condenser, for absorbing NO.sub.x gases in water, to provide in a stream of raw nitric acid-containing residual NO.sub.x gas and a tail gas including NO.sub.x gases. The system further includes a mechanism for splitting the tail gas into a first tail gas stream and a second tail gas stream; and a mechanism for adjusting the amount of tail gas being split.

A process and system are disclosed for producing a lithium product from a solution comprising lithium nitrate. The solution comprising lithium nitrate can be obtained by reacting a lithium-containing metal silicate with nitric acid. The process and system comprise subjecting the solution comprising lithium nitrate to a first thermal treatment procedure (in one or more heated vessels) in which water and nitric acid (when present) are removed, and whereby a resultant lithium nitrate-rich crystal slurry is heated to produce a molten liquid. The process and system also comprise passing the molten liquid to a second thermal treatment procedure (in a further-heated vessel) in which the molten liquid is heated to substantially decompose lithium nitrate to lithium oxide.