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Determination of Molybdenum in Ferrotungsten with Citric Acid Masked Tungsten Thiocyanate Spectrometric Method

Category: Tungsten Information
Published on 02 September 2015

The sample is decomposed with sodium superoxide,than to separate iron and manganese from tungsten and molybdenum. After complexing the tungsten with citric acid,the molybdenum content is determined in about 11 mol/L sulfuric acid with thiocyanate spectrometric method using copper salt as catalyst and sulfocarbamide as reductant. The analytical results are satisfactoty.

Citric acid is a weak organic acid with the formula C6H8O7. It is a natural preservative which is present in citrus fruits. It is also used to add an acidic or sour taste to foods and drinks. In biochemistry, the conjugate base of citric acid, citrate, is important as an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms. It consists of 3 carboxyl (R-COOH) groups.

Citric acid is a commodity chemical, and more than a million tons are produced every year by fermentation. It is used mainly as an acidifier, as a flavoring, and as a chelating agent.

 

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System And Method For Processing Ferrotungsten And Other Tungsten Alloys

Category: Tungsten Information
Published on 02 September 2015

Systems and methods for refining or otherwise processing tungsten alloys, including ferrotungsten powder and articles formed therefrom, and methods for detecting the presence of the same. The methods include at least one of magnetically-separating and particle-size-separating ferrotungsten or ferrotungsten-containing powder. In some embodiments, powder may be separated to remove fine particles, and optionally to separate the remaining particles into fractions containing selected particle size distributions. The powder additionally or alternatively may be separated into at least magnetic and non-magnetic fractions. In some embodiments, portions of two or more size and/or magnetism fractions are mixed to provide a ferrotungsten-containing feedstock. Selected fractions resulting from the size and magnetism separation steps may be utilized to provide a ferrotungsten-containing feedstock from which articles are produced and which may include additional components.

 

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Development Of Desulphurization And Dearsenication Craft Under Vacuum For Ferrotungsten

Category: Tungsten Information
Published on 02 September 2015

Desulfurisation is a chemical process for the removal of sulfur from a material. This can involve either the removal of sulfur from a molecule (e.g. A=S → A:) or the removal of sulfur compounds from a mixture such as petrochemicals or flue gases.

Many of these processes are of great industrial and environmental importance as they provide the bulk of sulfur used in industry (Claus process and Contact process) and also reduce the release of harmful sulfur compounds into the environment (hydrodesulfurization, flue-gas desulfurization); particularly sulfur dioxide (SO2) which leads to acid rain.

It introduces crafts and related factors of desulphurization and dearsenication craft under vacuum for ferro-tungsten. By adapting to the craft, the average arsenic content in ferrotungsten can reach 0. 0352% , the average sulfur content in alloy can reach 0. 0152%, the average dearsenication ratio and desulphurization ratio can reach 27% and 76% respectively.

 

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Discussion On Dephosphorization Technology For Smelting Ferrotungsten

Category: Tungsten Information
Published on 02 September 2015

In line with the mechanism of the suitable basic slag,which can be formed at the melting oxygen stage in the basic electric arc furnace,can remove most of phosphorus in the molten steel,we add certain volume of scheelite during the smelting ferrotungsten process. Slag basicity can be increased and foamed-slag can be formed to remove the phosph-prus in ferrotungsten at the refining stage.

Scheelite is a calcium tungstate mineral with the chemical formula CaWO4. It is an important ore of tungsten. Well-formed crystals are sought by collectors and are occasionally fashioned into gemstones when suitably free of flaws. Scheelite has been synthesized via the Czochralski process; the material produced may be used to imitate diamond, as a scintillator, or as a solid state lasing medium. It was also used in radium paint in the same fashion as was zinc sulphide, and Thomas Edison invented a fluoroscope with a calcium tungstate-coated screen, making the images six times brighter that those with barium platinocyanide; the latter chemical allowed Röntgen to discover X-rays in early November 1895.

 

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Determination of Tungsten in Ferrotungsten by Thiocyanate Colorimetry

Category: Tungsten Information
Published on 02 September 2015

Colorimetry (American English) or Colourimetry (British English; see spelling differences) is "the science and technology used to quantify and describe physically the human color perception." It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color perception, most often the CIE 1931 XYZ color space tristimulus values and related quantities.

According to the characteristic of tungsten being complexed in medium of phosphoric acid, the specimen is reduced via stannous chloride, catalyzed by titanium trichloride, in strongly acidic medium, tungsten and thiocyanate form yellow complex, and then photometric analysis is made.

 

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Discussion On Smelting Ferrotungsten With Sheelite Concentrate

Category: Tungsten Information
Published on 02 September 2015

Scheelite is a calcium tungstate mineral with the chemical formula CaWO4. It is an important ore of tungsten. Well-formed crystals are sought by collectors and are occasionally fashioned into gemstones when suitably free of flaws. Scheelite has been synthesized via the Czochralski process; the material produced may be used to imitate diamond, as a scintillator, or as a solid state lasing medium. It was also used in radium paint in the same fashion as was zinc sulphide, and Thomas Edison invented a fluoroscope with a calcium tungstate-coated screen, making the images six times brighter that those with barium platinocyanide; the latter chemical allowed Röntgen to discover X-rays in early November 1895.

In smelting ferrotungsten,using sheelite concentrate to substitute partly wolframite concentrate. By reforming process,charging an enormous amount of low phosphorous,low calcium oxide and high iron oxide during refining,picking and diluting stages respectively,then can decrease the ferrotungsten production cost and obtain obvious benefit.

 

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Extraction of Ferrotungsten from Ores with Low WO3 Content

Category: Tungsten Information
Published on 02 September 2015

Aluminothermic SHS reaction was explored as a possible route to manufacturing ferrotungsten alloy (FeW) from an ore concentrate. Changing green composition, i.e. the amount (x) of Al, it was possible to control the composition and microstructure of resultant alloys. Regardless of green composition, the final product always consisted of three phases: W, FeW, and Fe-Al-W. Compositions of the W and FeW phases were independent of x, while the Al content of the Fe-Al-W phase grew with increasing x. An alloy most closely fitting specification requirements was synthesized from green mixtures with a slightly lower amount of Al as compared to a stoichiometric one.

 

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Tungsten Carbide Tipped (TCT) Core Drills

Category: Tungsten Information
Published on 02 September 2015
TCT core drills are made from Tungsten carbide material on their tips. Tungsten carbide is a very hard man material and supposed to be one of the hardest material made by man. TCT core drills are more expensive then HSS core drills but are faster and easy to make bigger holes. There are also different types in TCT core drills. TCT core drills are cheaper for bigger diameter i.e. above 41 mm. They are very efficient for cutting hard material. The chances of tip breakage in TCT core drill is more compared to HSS Core drills. TCT core drills has a disadvantage that it can not be reground. Once the TCT core drill is damaged it has to be thrown away, it can not be re used like the HSS core drills. It is always recommended by manufacturers to use TCT core drills only for larger diameter and for very hard material, while giving priority to HSS core drills because of its price and re-sharpening advantages.
 
TCT Standard
 
A Standard TCT core drill is a with tungsten carbide tips. These types of core drills are now available in vast range of diameter, for up to 150 mm. These are popularly used core drills on magnetic core drilling machines. These core drills are popularly used to drill materials like railway tracks, structural steel,stainless steel, cast iron, etc.
 
TCT with hard coating
 
The TCT core drills with hard coating are core drills with a coating on it, generally TiN coating. This makes the core drills more resistant to heat, longer tool life and even removal of chips just like the advantage of HSS core drill. The biggest advantage of hard coated core drills is that these cutters are very good for cutting larger diameters on hard material. These core drills are popularly used to drill materials like corroded or weathered material, structural and stainless steel.
 

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Tungsten Carbide Annular Cutter(Core Drill) General Concept

Category: Tungsten Information
Published on 02 September 2015
An annular cutter (also called as core drill, core cutter, broach cutter, Trepanning drill or cup-type cutter) is a hollow, multiple cutting edges cutting tool used to make/drill holes in ferrous and non-ferrous metals. An annular cutter cuts only an annular groove at the periphery of the hole and leaves a solid core or slug at the hole center.[1] Annular cutter is a substitute for slower, more expensive and less efficient Twist drills and Hole saws. The function of Annular Cutters is more or less same as a hole saw but differs in geometry and material. Annular cutters are faster, easier and are more accurate than the conventional twist drills or drill bits.
 
An annular cutter or core drill removes the material from the metal to create cylindrical holes in a circular cross section. An annular cutter, unlike drill bits, cuts only on the periphery of the hole to be made. Annular cutters use almost the same method as concrete core drills, but are for metal drilling. An annular cutter is a multipoint cutting tool and is made from material like high speed steel and tungsten carbide tips.
 
Annular cutters are available in different sizes generally starting from diameter 12 mm (1/2’’) to 200 mm (7 7/8’’) and larger if required. The length of the annular cutter can be achieved depending upon the thickness of the material to be drilled. In the market the lengths 30 mm, 55 mm, 75 and 110 mm annular cutters are popularly available. These sizes though vary from manufacturer to manufacturer. The annular cutter’s material should be harder than the material to be drilled. Therefore there are various types of material used to manufacture annular cutters, for example different types HSS and TCT material. Annular cutters are also called as core drills because, after drilling hole, the drilled material is ejected from the cutter in the form of a cylindrical blank, this blank is called a core.
 
The first annular cutter was invented by Mr. Dough Hougen which he patented in 1973.[2] The High Speed Steel annular cutter was invented in 1983 by Michael Beharry [3] and the tungsten carbide tipped annular cutter was invented in 1985 by Mikiya Toshio and Shoji Michihiro.[4]
 
Though people use annular cutters on conventional drilling machines like radial drilling machines or pillar drilling machine, it is not recommended because these machines have very high RPM which creates high tool breakage risk for annular cutters as they are hollow unlike solid twist drills. It is always recommended to use an annular cutter or core drill with a magnetic core drilling machine (also called as magnetic drill, magnetic base drilling machine, etc.) as these machines are slower. A magnetic drilling machine is ideally made for using annular cutters.
 
 

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Tungsten Carbide Nozzle Grain Growth

Category: Tungsten Information
Published on 02 September 2015

The grain growth problem, which is an inevitable problem during WC-Co cemented carbide nozzles liquid phase sintering process. While there are two main patterns of the grain growth, one is WC particles growing uniformly, approach the growth is constant. The other one is some WC grains is growing in advance. However, these two patterns of the grain growth is not independent, and they can be existing and occurring in the same time.

Generally, to control the constant growth of grains and avoid the regional growth, which is able to ensure the density of the material. During the sintering process, the regional WC grain growth and become thick, which is the source of tungsten carbide nozzle cracks appearing. Therefore, adds appropriate amount of the WC powder grain growth inhibitors, which can be beneficial for suppressing the growth of grain and improving the lifespan.

 

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