Liquid-Film Method for Ammonium Paratungstate Production II

Currently the main technology key of emulsion liquid membrane is the stability and membrane bursting technology. It’s different required for the stability of the liquid membrane extraction and bursting membrane phase , the former one requires a high stability while the latter one want a low stability. Currently it’s difficult to control the stability and longevity; rupture technology and organic reuse and recycling phases within phase related, which directly affect the economic effects of liquid film method, the effect of different formulations of liquid membrane rupture is not the same, and therefore rupture technology also needs to be tested. For the study of surfactant and a carrier, but also directly affect the technical and economic effects of liquid film. In addition, industrial wastewater treatment, since the dissolution of membrane components may cause secondary pollution, these problems can be in research and development in the film is further resolved.
 
With crude sodium tungstate or tungsten concentrates obtained tungsten fine mud alkali fusion dissolved in water as feed solution pH adjusted to 8-9 after removing impurities of silicon, without removal of phosphorus, arsenic, molybdenum at room temperature for a laboratory directly Intermittent Liquid Membrane ,, according to the orthogonal design of optimum operating conditions, within 5min inner aqueous phase directly from ammonium paratungstate (APT) crystallization. Extraction rate of 99.85%, the purity level of product standards. Article on various factors depth study, proposed a level of continuous countercurrent flow, low cost, it is a promising new approach.

APT

Tungsten Alloy Ballast WeightsⅡ

Tungsten alloy is able to become the first choice of ship ballast weights material , primarily because of its own great advantages.
 
1, High density
 
The density of tungsten alloy is up to 18.5 g / cm3, 65% higher than the density of lead alloy. Nowadays, because of its defects, lead has faded away from people’s views, the density of steel and iron or other materials were lower than tungsten alloy, therefore, tungsten alloy can well take over this position and become the preferred weights material that used in various fields.
 
2, Good wear resistance, corrosion resistance
 
It is well-known that tungsten has a high density, and it’s a heavy material, it can keep no deformation even at a very high temperature or strong impact, so it’s suitable for long-term immersion in seawater, and also particularly suitable for ballast weights.
 
3, No environmental pollution
 
Since using lead material to produce ballast weights, or seawater ballast weights etc, would causes environmental pollution and abuse, but tungsten alloy is a green metal material, it won’t produce toxic substance during producing and processing. Thus, tungsten alloy weights is the most suitable for the ballast weights.
 
In addition to the above advantages, tungsten alloy also has other series of excellent physical and mechanical properties of good machining, welding characteristics, and can adapt to the dynamic or static installation. It applies not only to the ship's ballast weights, but also applied to the counterbalance weights components of a variety of instruments and engines. Such as the counterweight element on the "Spey" engine and counterweight element for controlling the Sub-throttle of fuel amount adjusted at a high speed and so on.
tungsten-alloy-ballast-weights

Tungsten Alloy Ballast WeightsⅠ

For most boats and ships, they often face with many force majeure of natural factors when they sail in the sea. How to ensure ships to sail smoothly and safely is the most important issue for the all voyagers. Especially for cargo ships, when a cargo ship, full with cargo and discharged cargo after arriving destination port, its hull would be lighter, if it sails at this time, it will increase the risks of tipping. So, every boat should be equipped with ballast tanks, for storing ballast weights. An appropriate amount of ballast weights can ensure the propellers of ships to draft adequately, reduce the hull vibration to a minimum degree, and sustain propulsion efficiency and ensure stable and safe operation of the ship in the voyaging journey.
 
In addition, the ballast weights can also keep the time of shear force and tilting maintained of the ship within a safe range in the sailing process. Ballast weights are usually sand, stones or water, but injecting seawater as ballast weights would be likely to cause the invasion of adventitious species, such examples are not uncommon. With the development of international trade and economic globalization, about 80 percent of cargo is transported by ships, while the global approximately 10 billion tons of ballast water discharged in the strange port per year. The red tide caused in China's coastal side is due to the ballast water, which brings the adventitious species.
 
How to ensure the safety of ships sailing without causing marine environment pollution, the essential problem is to select the ballast materials. With a variety of metal materials continue to be discovered and utilized, this new type of high density tungsten alloy material has become the most popular current ballast material due to its small volume density and some other advantages.
tungsten-alloy-ballast-weights

 

Liquid-Film Method for Ammonium Paratungstate Production I

China has the most tungsten reserves in the world, occupying an important position in China's metallurgical industry. Ammonium paratungstate is the main raw material for metal tungsten production. Now extraction and ion exchange process are widely used in factories. The former one is that removing silicon, phosphorus, arsenic step by step after alkali boiling (or alkali fusion) of tungsten concentrates, adding Na2S make Mo become MoS3 precipitation, and then the supernatant was adjusted to pH 2-3, and extracted with a tertiary amine. Stripping with NH4OH. Therefore, to clarify the slot will go through stages of pH = 6. APT will then crystallize resulting in difficulty to normal operation. This problem is difficult to resolve from the formula, it is by strengthening stirring to dissolve the crystals again clarified or improved groove geometry of the internal structure of the practice. Although not required in addition to the ion exchange method P, As, Si but can not remove molybdenum, it is often the choice of Mo-containing low amounts of tungsten concentrate certain specifications. Although this method can be used directly with an alkaline feed solution, but due to the exchange a small amount of the material must first be diluted to contain WO3 25g / L or less, plus the rinse water is also large, and therefore of alkaline wastewater emissions pH10-13 Very large, wastewater treatment has become a burden, and waste water of these two methods can not be recovered in tungsten.
 
The concept emulsion film is N.N.Li proposed in 1968, it has attracted researchers States. Because it simulates the activity of migration biofilm on the migration mechanism enables highly enriched material against the concentration difference. It is the combination of extraction and back-extraction process carried out in a system where the same time, the reaction on the surface area is extremely thin film interface, plus the addition of a supported membrane, so its kinetic advantages far The reaction solution is better than the body conducted the mass transfer rate, efficiency and selectivity than the extraction process. This new technology is currently developing a forward unit operations, the international industrial application is first started University of Graz, Austria, for the recovery of zinc from waste water, followed by the Institute of Environmental Science, South China University of Technology for the removal of phenol wastewater.

APT

Nano Tungsten Copper Mixed Powder of Tungsten Copper Electrode Preparation

Compared with traditional powder metallurgy (PM), tungsten copper electrode nano composite material including powder milling, compacting and sintering process, but due to the characteristics of nano particles, there are some differences between traditional powder metallurgy and nano tungsten copper mixed powder preparation.

1. Direct mixing

The nano tungsten powder and copper powder directly mixed according to a certain proportion, which has many methods, such as ultrasonic mixing, mechanical stirring, ball milling and so on. The mixing process should at the inert gas atmosphere, otherwise the nano powder will be oxidized easily.

2. Mechanical alloying (MA)

MA refers to the W, Cu metal powder stirring energy ball milling, high energy planetary ball mill or rotor, while using inert gas to prevent oxidation of the powder during the milling process. In the process of mechanical alloying, collision with a metal ball leaving the powder on powder body ingot refining, and mixing the powder collision between recurrent, so that each element powder blended to achieve a very uniform degree and form of nano crystalline supersaturated solid solution and amorphous phase. In addition, the facility and conditions it required is simple, which is the most widely studied by the researchers and scholars in the world.

3. Composite powder coreduction

Owing to tungsten oxide and copper oxide are easily reduced to the metal by hydrogen (H2), Uses composite powder reduction to prepare a uniform distribution of tungsten-copper composite powders has been one of the hot researches. n recent years, researchers have found that using a special co-reduction method can be directly sintered into dense tungsten-copper composite powder having a uniform fine grain structure, there are some applied to the preparation of parts for industrial use.

There are two methods to the powder preparing, one is that tungsten oxide and copper oxide powder are mixed with water pulping, grinding, spray drying, and reduction with hydrogen was obtained spherical powder, powder of tungsten phase and a copper phase distribution more uniform, wherein the particle size of the tungsten 1-3μm. Then the spherical powder can be pressed and sintered to obtain a dense, fine-grained tungsten-copper composite material. Another is uses ammonium metatungstate reacted with copper oxide complex oxide, copper which is about 26%. Cu is the core, which tungsten grain surrounded by. Although this tungsten-copper composite powder pressing and sintering the resulting tungsten copper material compared to infiltration method can be better thermal conductivity properties as well as the overall performance, but the process is relatively complex, low productivity shortcomings.

 

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