Denitration catalyst, being the hard-core of SCR denitrification technology, will lose activity due to wear and clogging, alkali metal poisoning and other reasons in the running process. Besides, it’s hard to separate V₂O₅ and WO₃ out, because the two main components are so similar metal oxides, further more, there are T12 and glass fiber exist in the waste flue gas denitration catalyst. Nowadays, the way to deal with waste catalyst is landfill in universal, the technology about it is still in research stage. A research has introduced a method for recovering W and V from waste denitration catalyst, and the steps are as follows:



1. Grinding the catalyst and adding sulfuric acid to acid splitting, and then add water to obtain titanyl sulfate solution;
2. Filter the solution that obtained in step 1, collecting the residue for further using, and hydrolysis after the filtrate being heated and concentrated to generate product;
3. Filter hydrolysis products, and carry out settlement;
4. Take supernatant after filtering, and adding NH₄Cl in the excess amount; filtering again after fully reaction to obtain ammonium metavanadate; then recovering V in the form of pure V₂O₅ from ammonium metavanadate by calcine;
5. Add excess amount of ammonia with 10%~28% concentration into residue obtained in step 2; and then heated to 80~100℃ to generate APT crystal; then carry out drying and calcinations to recover W in the form of WO₃.

The related researchers adapted different proportions of tungsten-copper alloy (W-20Cu, W-30Cu, W-40Cu) products after infiltrated for cold rolling and intermediate annealing at the deformation process, each pass compression 5% -10%, up to 50% of the total final amount of deformation. Wherein the amount of deformation <25%, the material is only deformed in copper; when the amount of deformation reaches 50%, tungsten materials began to stretch along the rolling direction. Some foreign scholars sintered density of the obtained tungsten copper W-40Cu material extrusion, hot forging and cold forging obtained after tungsten copper rod; a sintered density of only 75% of the tungsten copper plate W-40Cu after cold rolling billet can be made of tungsten copper sheet; and cold rolled billet, and then cold-rolled, cold drawing was also prepared tungsten wire having a diameter of 0.3mm of material.

This deformation after machining tungsten copper alloy has fully dense tissue, mechanical strength and excellent electrical and thermal conductivity, which can be widely used in many areas of application and to meet different needs. Compared with cold deformation processing, hot deformation process refers to the metal under the recrystallization temperature of the plastic deformation, the common processing methods includes bending forging, hot pressing and pulling molding. Different from cold deformation processing (Since the process breaking the original balance of forces inside the metal, resulting in the release of stress, the original force balance is broken and the deformation, which does not reach yield point of the metal material), metal hot deformation processing has plastic deformation and reaches the yield point of the material. However, it is difficult to control the processing temperature, which can not ensure the structure and comprehensive properties of tungsten copper completely.

Tungsten copper product is commonly fabricated by powder metallurgy (PM) and infiltration. Due to the large difference of hardness and melting point of tungsten (W) and copper (Cu) and completely immiscible, it is also known as two-phase psudoalloy. Through its incorporation of tungsten powder or after forming part of a mixed copper powder special suppress internal communication pore tungsten skeleton, tungsten copper alloy is further formed by copper infiltration process with relatively high density, the excellent properties. At present, there have been superfine nano-crystalline tungsten-copper alloy, the microscopic structure is more reasonable and stable, relative density and intensity has also increased significantly, but its plasticity and ductility is relatively low, can not meet the particular requirements of some products (such as sheet, for wire, foil, etc.), and therefore the study of the deformation processing of tungsten copper alloy material has also become a hot topic.

For the deformation processing of tungsten copper material, we can specifically divide it into two types, one is cold deformation processing, another is heat deformation processing. From the definition, cold deformation processing is a kind of plastic deformation processing under recrystallization temperature. With the development of the core technology of mechanical processing industry, the production of more and more molded parts are manufactured by cold mold, types of cold deformation of the mold used more. Volume cold forging (cold heading, cold extrusion, stamping, etc.); sheet metal stamping (such as drawing, blanking, cutting, punching, etc.); material rolling (cold rolling wheel molding, etc.). Although many types of cold deformation of the mold, different working conditions, performance requirements are different, but the basic work in close: that was so in the cold state of the metal deformation, withstand greater shear force at work, pressure, bending force, impact and friction.

Nanorod is rod-shaped nanoparticles scale from a few nanometers to hundreds of nanometers; it is relatively stable and abundant physical and chemical properties. Surface plasmon resonance wavelength nanorods with aspect ratio can be changed. Because of its unique optical, photovoltaic, solar thermal, photochemical, and molecular biological properties, nanorod caused many concerns by materials scientists, biochemists, physicians, physicists, micro- Electronics engineers and other scientists on the extensive and intensive studies.

In the growth process of tungsten trioxide nanorods, sodium ions preferentially adsorbed in the surface of the tungsten trioxide crystal, the crystal surface inhibits the growth of tungsten trioxide nanorods under visible light, which shows better catalytic performance, and gas sensing performance, the test results show that tungsten trioxide nanorods operating temperature is low, and trimethylamine trioxide has a high sensitivity and good response and recovery time, the material shows a good prospect.

When the molar ratio of sodium sulfate and sodium tungstate is 4: 1, XRD diagrams of the various hydrothermal can be seen when the water heated for longer than 24h, the product is pure hexagonal tungsten trioxide in the hydrothermal time 6h , the hexagonal tungsten trioxide (200 planes) has emerged, and (001) planes appeared until 12h, which suggests that the early stages of tungsten trioxide hexagonal crystal growth (200) crystal surface is an advantage, it has adsorbed in solution; reducing the chance of tungsten trioxide crystals to the (200) plane growth of tungsten trioxide to make it another advantage crystal face (001) growth, the (001) crystal face has a significant growth after 48h, tungsten trioxide nanorods becomes in the hydrothermal.

Tungsten trioxide nanorods are synthesized by 2.77g of sodium tungstate and 4.77g of sodium dissolved in 67.5ml of water , stirring, adjusting 3mol / L hydrochloric acid to pH 1.5, stirring it 30min, heating it at 180 ℃ in above solution 48h, washing three times with ethanol, drying at 65 ℃ in the environment, it can be prepared nanorods of tungsten trioxide, which is a single crystal nanorods.

Tungsten trioxide nanorods are dissolved by sodium tungstate and sodium sulfate water, after stirring, adjusting the pH value, washing and drying to obtain tungsten trioxide nanorods. In the synthesis process, the selection of the sodium salt can be as director of synthesizing tungsten trioxide nanorods, and director is not the product of rod-shaped morphology.

Preparation of tungsten trioxide obtained nanorods can be observed by electron microscopy. Nanorods is 1-5μm in length, between 25-40nm in diameter, the tungsten trioxide has a high aspect ratio nanorods; the diameter of single trioxide nanorod is 30nm, the lattice fringes are clearly visible, this indicating is higher degree of crystallinity nanorods; this also shows the two intertwined lattice fringes, and hexagonal tungsten trioxide contrast can be found in the two planes are (001) and (200) planes, wherein the (001) planes are grown.

Although the tungsten trioxide nanorods preparation process shows a good prospect, it is still in the laboratory research stage. We should increase research and development, strengthen exchanges and cooperation in various fields between basic researches and make its research and application level to be improved, make it as soon as possible apply to industrial production.

In this mechanism, except that the corner of the grinding disc groove diameter, V-channel angle and other geometrical parameters, but also with three abrasive disk rotational speed related. Through three platen speed adjustments can change (within the range of values of -90 ° -90 °) the angle of rotation. In addition, ball blank can be done changing the relative orientation of the spin axis of the grinding motion, its grinding trajectory line is he central axis of the shaft space sphere curve. In this way it is possible to cover the entire surface of the ball blank uniformly conducive to ball billet surface to obtain a uniform and efficient grinding. However, while this method in experiments to ensure good processing accuracy and processing efficiency, but in the actual production practice of commissioning and maintenance there are some difficulties to promote the production and use.

The double rotation grinding by the relevant domestic researchers first proposed, which is based on self-active control angle grinding, under the premise of maintaining the corner from the active control function, the upper lapping plate in the process of fixing the circumferential direction, and applied to ball billet certain elastic load, such that the larger ball blank allowance subject to greater loads, which also meet the size of the ball milled selective conditions. In addition, it uses two separate grinding trays rotating components, simplifying the mechanical structure also reduces the difficulty of assembling and processing (grinding process, the grinding tray during the grinding process does not need to rotate, so that the lower plate coaxial low requirements). But this process also has some problems, due to cobalt tungsten carbide ball in the grinding process prone to greater inertia, which will grind the whole trajectory and process have a certain impact, and high hardness of tungsten carbide cobalt will be on the ball trench uneven wear such precision can not be guaranteed.

Eccentric V-slot grinding, its axis of abrasive tray rotation and V-slot has a certain offset distance, which makes the ball billet revolution center and the center of rotation of the tray is not in the same straight line, and the contact point on the ball billet grinding tray along the upper abrasive tray radial direction. Compared with conventional V-slot grinding, it can achieve better spherical deviation. Chinese scholars also puts forward the optimization program, even if the eccentric disk and V-groove grinding discs rotate simultaneously, by adjusting the rotational speed of the upper and lower grinding disc, grinding track is sufficiently divergent, thus weakening offset the adverse effects of polishing uniformity.

Due to it has high hardness, high density and high strength, tungsten carbide ball plays an significant role in some oilfield or offshore drilling, which takes place of steel ball and ceramic ball gradually. The conventional grinding process itself due to mechanical constraints as well as some human factors can not exclude the influence can not be guaranteed tungsten carbide blank ball consistency and performance stability. Therefore, many related researchers has studied on tungsten carbide ball high precision grinding methods, which mainly includes eccentric V-slot grinding, angle of rotation controlling and double rotation grinding.

Firstly, since grinding angle active control is an idea of some of the relevant scholars from abroad first proposed, which is also known as three sets of coaxial grinding method. It is based on conventional V-slot grinding method, V-slot portion of the lower plate has been separated, so that the entire body is composed of three independently rotatable grinding disc composition, and then to adjust the ball from the corner of the blank by controlling the speed change three of grinding tray, the schematic given as follow: