Aimed at research and Design Institute of ammonium paratungstate the production waste water to put forward a reasonable process,so that the treated wastewater discharges standards.The results showed: the two methods could meet the national discharge standard.One is waste acid neutralization-lime precipitation,two is sulfuric acid neutralization-lime precipitation of arsenic and fluoride can meet the national wastewater discharge standards;fluoride ion concentration was increased to700mg/L,the method can also be used.

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Connected with the examination of the thermal polycondensation of ammonium paratungstate pentahydrate the chemical and morphological properties of intermediate phases formed during the thermal decomposition of APT have been investigated. We have studied the pH and the turbidity of the aqueous solutions of the intermediate phases, the solubility of the phases, and their rehydratation capability as well as the morphology of the crystallite granules and the grain size distribution. These properties of the original APT have been related to the same properties of the products of decomposition formed between different temperature ranges. The results obtained show unambiguously that each of the above mentioned properties suddenly changes in the temperature range 225 to 250°C. This temperature range coincides with the formation temperature of a new phase called APT II. The most probable formula of APT II is (NH₄)₈ [H₂W₁₃O₄₃(OH)₂]·H₂O.

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Tungsten carbide powder is conventionally produced by carburization of tungsten powder by carbon black in a solid–solid reaction. This paper reports the carburization of ammonium paratungstate by methane to yield tungsten carbide at low temperature in short times. The carbide powder is fine grained and has specific surface area around 35 m²/g. This makes the powder interesting for catalysis and fine grained hard metals. The influence of reaction parameters such as temperature, gas flow, composition of the reaction gas and powder charge are investigated by means of gas chromatography and XRD with Rietveld refining. The overall reaction time is the sum of reduction and carburization times of the sequential reactions. Some parameters, like gas composition affects only the carburization rate, other parameters, such as gas flow affects both reactions.

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The method is disclosed for producing ammonium paratungstate from cemented tungsten carbide which comprises subjecting the cemented tungsten carbide to electrolysis by passing about 0.5 to about 20 volts through an ammoniacal solution selected from the group consisting of ammonium hydroxide-ammonium chloride solution, ammonium hydroxide-ammonium carbonate solution, and ammonium hydroxide-ammonium sulfate solution, wherein platinum and the cemented tungsten carbide serve as the anode and wherein the anode is immersed in the solution, to decompose the cemented tungsten carbide and form a solution of ammonium tungstate from which is crystallized ammonium paratungstate.

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To obtain highly purified, lamp grade ammonium paratungstate crystals from any of several different tungsten ores, the ore is reduced to finely divided status and slurried in heated HCl solution to convert tungsten values to WO₃.H₂ O. Recovered tungstic oxide is washed and dissolved in heated aqueous solution of sodium carbonate or sodium hydroxide with the pH maintained at about 8 to 8.5 to form soluble sodium tungstate. Sodium hydroxide is added to raise the pH to about 10.5 to 11.5, and magnesium chloride is added in amount sufficient to somewhat neutralize the solution. Sodium hydroxide is added to raise the pH to about 10.5 to 11.5 to precipitate as hydroxide the magnesium and additional metallic impurities. At least one of ammonium sulfide and thioacetamide is and the heated solution is acidified to a pH in the range from about 2 to 3 to precipitate any molybdenum as MoS₃. The tungstate solution is then contacted with an organic, water-immiscible ion exchange liquid in which the active ingredient is an amine salt to extract the tungsten values. Tungsten values are then stripped from the ion exchange liquid with ammonium hydroxide to form ammonium tungstate solution, which in turn is separated. From the ammonium tungstate solution is crystallized highly purified ammonium paratungstate. The process is adaptable to continuous type operation.

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The method is disclosed for producing relatively pure ammonium paratungstate from an impure tungsten solution. The method involves first adding hexamethylenetetramine to the tungsten solution and adjusting the pH to from about 1.0 to about 2.0 with a mineral acid to form a first precipitate of a tungsten hexamethylenetetramine product, which is then separated from its mother liquor. The precipitate is then slurried in water and the pH adjusted to from about 7.0 to about 8.5 with ammonia to dissolve the precipitate. The resulting solution is then adjusted to from about 1.0 to about 2.0 with a mineral acid to form a second precipitate of the tungsten hexamethylenetetramine product which is then separated from its mother liquor. The second precipitate is then slurried in a solution of water and sufficient ammonia to form ammonium paratungstate which crystallizes out on evaporation of the slurry. The ammonium paratungstate is then separated from its mother liquor.

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Spinning means that your dart rotates (spins) when you throw it. Some players that have noticed this spin are concerned whether this is okay or a bad thing.

I don't think that spin is a bad thing. It is an additional source for errors, as it is an additional movement, but on the other hand spin also adds stability. In my point of view these two things eliminate each other, so there is no use worrying about it. In no case should you try to consciously make your darts spin or consciously try to eliminate spin.

Spinning has nothing to do with darts tuning. It is not determined or influenced by the flight/shaft system. It is determined by your personal throw.

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Darts tuning is meant to determine a setup for your darts that fits your throw. When I am talking about setup I mean the flight/shaft system of the dart. This system is responsible for the aerodynamic behavior of your darts. It must meet the requirements of darts physics (see the technics section for a closer look at this). The main parameter for determining the correct flight/shaft system for you is the angle at which the dart sticks in the board. Unfortunately you can only see this angle when you are playing on a steel tip board. If you are playing only soft tip then you should switch to a steel board for darts tuning.

correct board angle

The correct angle is within 10 to 60 degrees. Just like in the picture above. The more consistent this angle is, the better. For instance, if every dart of your 3 dart series sticks in a different angle then something is wrong. Most likely does your dart wobble considerably, which can only be reduced by serious practicing. However, using a bigger flight shape will also help here as it adds stability.

Generally, bigger flights ("standard" shape or bigger) will give a greater angle, while smaller flights (such as "pear" shape) will give smaller angles. Note that when you are doing darts tuning always use the same shaft for comparison between flight shapes. Shaft length and shaft material have a strong effect on the flight/shaft system.

Also note that shaft weight (or even flight weight!) also have influence on this angle. The heavier the shaft or flight is, the smaller the angle will be. This is important when you decide whether you will use nylon or the heavier aluminum or titan shafts. The shaft rings can also influence this, as they make the shaft heavier.

Darts tuning needs work and patience. It should be done over a couple of days to eliminate possible daily variances in your throw. A good starting setup for darts tuning is middle length nylon shafts with "standard" size flights. From this initial setup you can continue working, depending on whether your angle is too big or too small.

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There are some options for outs with 2 darts left in hand. A dart thower need to respectiving single's  treble and take right way. The first region from 101 to 110 contains 4 numbers that can be shot out with 2 darts over the bull's eye. Here we go :( Trebles, doubles, singles: T20: treble 20D20: double 20 20: single 20 orT13: treble 13D13: double 1313: single 13and so on...)

2Dart Outs 110 - 101

T20 - D15 means: first dart treble 20 second dart double 15 (no third dart given: 2-dart out shot)

110 best option T20 - D2

107 best option T19 - D25

104 best option T18 - D25

101 best option T17 - D25

2Dart outs 100 - 71

Within this big range all numbers require a treble + a double. This table is pretty much like the usual "out charts" you might know, with the one exception that I give more variations when possible. For a better understanding of outs it will be very helpful if you compare these options with those options given for 3-dart outs. If there are differences, try to understand why!

100 best option T20 - D20

98     best option T20 - D19

97     best option T19 - D20

96     best option T20 - D18

95     best option T19 - D19

94     best option T18 - D20

93     best option T19 - D18

92     best option T20 - D16

.....

This is the "magic" number range. If you want to have a "guaranteed" dart at a double then you have to go for the single that leaves bull's eye.

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The grip is the most variable part of darting technique. In general you can use here what's comfortable for you. There are only a few DON'Ts you have to be aware of.

 The technique to grip dart:

You simply have to find your own grip. Everything that meets the requirements and can be handled well by you is good. Don't simply copy other players. Work it out on your own. You can of course try grips of different people for curiosity, to compare and find out which parts of it could fit you, or to learn about technical connections and improve your knowledge on this, but you are an individual, and grips are as individual as people. Don't get used to the habit of trying to find your 'weekly new and revolutionary grip'. Try for a while, find a suitable one, and then practice and use it.

The picture shows my standard grip - 3 fingers on the barrel (the 4th finger is not touching, although it might look like this on the picture). The small finger is spread away slightly.

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