Silicotungstic acid also known as dodeca-tungstosilicic acid tungstosilicic is white or yellowish deliquescent crystals. Its physical properties are shown below: chemical formula: H4O40SiW12, molecular weight: 2878.17, Solubility: 0.1g/ml (in water), CAS registry No.: 12027-38-2. Silicotungstic acid easily solute in water and alcohol, after dissolved the the solution is clear and transparent, but when it heat will dissolve in its crystal water and heated to 600~650℃ will decomposition. H4O40SiW12 mainly used in biochemical reagents and basic dye mordant. To seal and placed in dry place when storage and transportation.
Silicotungstic acid producing processes are as follow: using ammonium paratungstate as raw material, after conversion, mix silicon, exchange, evaporation and concentrated and other processes to obtain products, thereby preparing silicon tungstate. This producing method processes are reasonable and products have good quality, what’s more, it is kind of non-polluting method. It will be a new road for non-ether produced silicotungstic acid and silicon tungstate.

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Tungsten ore obtains cheelite and wolframite. Modern processing methods dissolve scheelite and wolframite concentrates by an alkaline pressure digestion, using either a soda or a concentrated NaOH solution. The sodium tungstate solution obtained is purified by precipitation and filtration, before it is converted into an ammonium tungstate solution. This stage is carried out exclusively by solvent extraction or ion exchange resins. Finally, high purity Ammonium-Paratungstate (APT) is obtained by crystallisation, with the formula (NH₄)₁₀(H₂W₁₂O₄₂) ·4H₂O.

Wolframite concentrates can also be smelted directly with charcoal or coke in an electric arc furnace to produce ferrotungsten (FeW) which is used as alloying material in steel production. Pure scheelite concentrate may also be added directly to molten steel.




 

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Tungsten is usually mined underground.  Scheelite and/or wolframite are frequently located in narrow veins which are slightly inclined and often widen with the depth. Open pit mines exist but are rare.

Tungsten mines are relatively small and rarely produce more than 2000t of ore per day.  Mining methods for tungsten ore are not at all exceptional and usually are adapted to the geology of the ore deposit.

Most tungsten ores contain less than 1.5% WO₃ and frequently only a few tenths of a percent. On the other hand, ore concentrates traded internationally require 65-75% WO₃.  Therefore, a very high amount of gangue material must be separated.  This is why ore dressing plants are always located in close proximity to the mine to save transportation costs.

The ore is first crushed and milled to liberate the tungsten mineral crystals.  Scheelite ore can be concentrated by gravimetric methods, often combined with froth flotation, whilst wolframite ore can be concentrated by gravity (spirals, cones, tables), sometimes in combination with magnetic separation. 



 

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It is obvious that flat-top tungsten carbide button would abrasive easily in some rock formation. According to incomplete statistics, almost flat-top tungsten carbide buttons are wasted when their 75% heights are not using. And the velocity of its plate enlarging is faster than the corrosion of the top. In addition, the longer diameter of the plat, which depresses the pressure between buttons and rock surface. Especially when impact load is insufficient, velocity of drilling would be influenced. So the efficiency of impact energy will be lower. Finally, due to the bottom of flat-top is flat, air inside the hole is hard to release to come into cushion when it has been set. So the pillar is unstable fixed.

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Cemented Carbide Mining Button Grades

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In order to accommodate applications where the X-ray flux is too high for both the detector and the electronics that process the X-ray spectrum, a “Collimator Kit” has been developed to collimate the primary X-ray beam. This system is comprised of standard 1.5 inch extender box which slides inside collimator housing.

The collimator housing can accommodate up to two tungsten collimator disks that are placed inside a bayonet holder in front of the detector. All tungsten disks are made of alloy HD17 (90% W, 6% Ni, 4% Cu). All Tungsten disks and spacers have a diameter of 0.625 inches. This Tungsten (W) Spacer /Collimator is 36 mm thick with a 300 µm hole. It is designed to stop and collimate x-rays greater than 100 keV produced from high energy tubes.

The picture shows the structure of tungsten collimator kit:

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Because tungsten alloy for X-ray attenuation ability is used for all kinds of radioactive source shielding components or container of a kind of ideal material. In addition, tungsten alloy is high density and environmental friendly. Tungsten alloy is usually used in the medical anti-radiation shielding materials and gamma knife.

Medical tungsten alloy radiation shielding material series, tungsten alloy grating blade, tungsten alloy protective tank -- for medical radiation shielding wall. Tungsten alloy can be produced as needle radiation shielding for medical radioactive liquid shielding. Tungsten alloy memory, cans, boxes and other containers used to store radioactive matter, collimator, for medical linear accelerator and nuclear technology applications in tungsten alloy series test container system collimator, Co60 radiation shielding.

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On the darts market, we can find different weight, price, materials between darts. But how can we distinguish between one variety from another?
 
Metals vary in density and weight, and so some metals are more ideal for darts than others. Lower priced recreational darts often use common metals like brass and copper. These metals are not very dense, so the heavier the dart, the thicker or longer it tends to be. Tungsten is very dense and heavy metal, allowing for barrels and shafts that are slim in design. Tungsten darts are mixed with nickel, iron and copper. Brass and nickel-silver are lighter metals in comparison to tungsten which is a very heavy and dense metal. It is seen that most of the good throwers use tungsten darts but if you are a starter then you would not be throwing tight groupings whatever dart you are using. On an average the size of a 20 gram tungsten darts are half the size of a brass dart which allows for tighter groupings on the board.

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Film components on tungsten points’ surface is WO₃, which is non-conductive, and whose dura layer possessing integrity and density, because it’s V_OX / V value (3.59) is more than 1. In the process of use, tungsten points’ surface would generate a tan oxide film layer, especially when they have been placed in a condition of high temperature and high humidity before using for a long time. And due to its poor conduction, the equipment would not operate.

Chemical formula:
V_OX=M_OX/D_OX
V=X*M_w/D_w
Among which,
V_OX refers to oxide volume;
M_OX refers to oxide molecular weight;
D_OX refers to oxide density;
V refers to the generated single oxide molecules’ metal volume;
X refers to single oxide molecules’ metal atom amount;
M_w refers to metal atomic weight;
D_w refers to metal density.
It is a loose, porous and incomplete oxide film when V_OX / V= M_OX* D_w/ D_OX* X*M_w＜1;
And the layer of metal oxide film possess integrity and density when V_OX / V= M_OX* D_w/ D_OX* X*M_w＞1.

 

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Tungsten Darts is considered a "gentlemanly sport". There are certain things that are expected of players, scorekeepers and spectators. While there are some players that do not follow these guidelines, it is usually because they are rude, ignorant or sore losers. Better players will not like to associate with these kinds of players, and often such activity can lead to the better players giving the offenders a "taste of their own medicine". Stick to these simple rules, and you will have a much more enjoyable game and make a lot more friends than enemies.

Sportsmanship:
Generally, all tungsten darts players are good sportsmen. They will shake hands at the beginning of a match and wish each other good luck. Similarly at the end of the game, they will shake hands and say "good game" or "nice shooting".

No distractions:
Much like professional golfers making an important putt, dart players like no distractions while throwing. This means:

Do not speak to the player who is shooting.
Don't go "ooh" and "aah" with each tungsten dart that is thrown.
Wait until all three darts have been thrown to say "good darts" or "right there".
Do not make sudden movements in front of the shooter. Scorekeepers should remain statue-still while a player is throwing.
Even better is to try to always stand behind the shooter outside his or her line of sight.
Spectators should try to keep movement and noise to a minimum while a player is shooting.
No one but the scorekeeper or a teammate should tell the shooter what has been hit.
What has been hit should only be announced if the shooter asks.
No one except a teammate, not even the scorekeeper, should ever tell the player what to hit next.

Score your tungsten darts before pull them:

This can avoid many arguments. If you write down the score on the board before you pull the darts from the board, you can show your opponent what you threw if there is a discrepancy.

Don't be a sore loser:

Appreciate what the other player has accomplished. If the other player bested you, live with it. Remember if you had thrown something really amazing, you'd be happy about it, so be happy for the other player too. Not only will this show that you are a lady/gentleman, but by keeping your own spirits up, you will remain relaxed and throw your next darts better than if you got angry or tense. I have witnessed many players (including myself and other members of my team) lose a game purely because they got angry and their game suffered because of it.

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