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Determination of chromium in vanadium - doped chrome powder by tungsten carbide

Abstract: The tungsten carbide doped vanadium-doped powder was transformed into a mixture of tungsten oxide, vanadium oxide and chromium oxide by sodium carbonate, dissolved by sodium hydroxide, filtered, Separation of tungsten and vanadium. After the precipitation is ashed, the sodium hydroxide is melted and the trivalent chromium is oxidized to hexavalent chromium with ammonium persulfate under acidic conditions and titrated with standard ferrous ammonium sulfate solution.

Key words: tungsten carbide; vanadium doped with vanadium; redox titration

Ultra-fine / nano-composite powder and microcrystalline refractory tungsten alloy preparation technology has become the focus of attention. As the ultra-fine grains (especially nano-grain) activity, in the sintering grow up quickly, if not controlled, it is difficult to obtain ultra-fine crystal powder. In order to suppress the rapid growth of ultrafine crystals in the powder, usually adding chromium oxide and vanadium oxide as Inhibitor, inhibit the growth of ultrafine tungsten carbide powder. At the same time, the addition of chromium oxide and vanadium oxide content of the inhibition of grain growth to play a key control. Therefore, the accurate determination of refractory tungsten carbide doped vanadium doped chromium powder vanadium, chromium content is very important. Vanadium determination is generally measured by colorimetric spectrophotometry, this study of chromium chemical analysis method. Tungsten carbide chemical analysis of chromium and vanadium chemical analysis methods have national standards and industry standards [1-2], and tungsten carbide doped vanadium doped chromium in the determination of chromium has been no national standards and industry standards, the determination of chromium in general With the oxidation-reduction titration [3], but this method can also be measured metal vanadium [4]. If the same time doped with vanadium doped chromium, the presence of vanadium will cause serious interference with the determination of chromium, resulting in high results. The advantage of this method is to separate the vanadium, but also the separation of the main tungsten, direct determination of chromium content. The results with high accuracy, good precision, easy operation and so on.

Application of the Techn ique of Carbon ized Tungsten in the Blast Furnace of Installation

ABSTRACT: The bell, valve and fire duct are important equipments to guarantee the production of blast furnace in the first iron mill of Jinan Iron and Steel Group Co. , the life span becomes bottleneck of conditioning technique and econom ic target to elevate in the blast furnace. The used deficiency of the bell , valve, fire duct and application of carbonized tungsten are introduced in this paper, effectiveness and benefits are analyzed in the first iron mill of Jinan Iron and Steel Group Co. .

KEYWORDS: Carbonized tungsten,Blast furnace,Bell Valve Fire duct

Jinan Iron and Steel Group Corporation, the first ironworks plant in 1958 to build, to today has developed 350m3 blast furnace 6, the use of double bell-style roof structure, the new 1750m3 blast furnace 2, the use of bell-free roof structure. With the improvement of the blast furnace hot air temperature, the improvement of the charge structure, the increase of oxygen enrichment and the amount of coal injection, some of the 350m3 blast furnaces are becoming less and less suitable for the production. The blast furnace size, The back end of the fire pipe of the inlet system increases with the increase of the blast furnace smelting intensity, and the wear and tear increases. Therefore, the original design of the size of the bell, relief valve and fire tube has been unable to meet the needs of blast furnace production. Due to the size of the bell leak, loose valve leakage, fire pipe air leakage caused by a lot of maintenance plans, blast furnace winds high, seriously affecting the blast furnace technical and economic indicators.

2 wet tungsten carbide technology: Tungsten carbide tungsten carbide technology (WCSP) is the use of high-energy ion injection technology, in a variety of complex shape parts of the steel matrix injection into the tungsten carbide, with high wear resistance of the tungsten carbide enrichment layer to 0. 3 ~ 0 5mm, tungsten carbide hardened layer to 1 ~ 1.5mm, with high hardness, high strength, high toughness, high wear resistance, mechanical parts surface modification process technology is an important breakthrough. Tungsten carbide injection into the steel matrix, the formation of metallurgical bonding, the concentration of each layer into a gradient, the microstructure of WCSP low magnification microstructure. Tungsten carbide and steel matrix both complementary advantages, so that the product surface with high hardness tungsten carbide, high wear resistance, high fatigue resistance, the heart has a steel base of high strength, high toughness. The surface hardness varies depending on the selected steel substrate and can vary between HRC45 and 64. WCSP hardness is not the only factor to measure wear resistance, soft matrix WC also has abrasion resistance, but slightly worse than the hard matrix wear resistance. Under the condition of severe wear and tear, the thickness of tungsten carbide hardened layer in WCSP is only 1 ~ 1.5mm, but all have good comprehensive mechanical properties and high wear resistance, and its service life is Material 3 to 10 times, and some more than 20 times.

3 blast furnace large, small material bell transformation blast furnace large, small bell damage mainly in the following two aspects:1) As the blast furnace smelting strength increases, the utilization factor increases, the unit time into the charge increased, large, small bell opening times increase, thus exacerbating the large and small clock contact surface wear. 2) As the furnace top pressure increases, in the large and small bells open the moment, the high pressure gas flow mixed with dust on the clock contact surface erosion, resulting in the emergence of the groove, serious when the clock closed, Will blow the furnace charge out of the furnace, and cause the blast furnace pressure fluctuations, to the blast furnace operation to adversely affect. For the blast furnace large and small bell wear reasons, the large and small bell of the contact surface structure transformation, and the use of wet tungsten carbide technology. Large and small bell after the transformation of the wear-resistant parts shown in Figure 1. After proven, from the use of the situation, the general material of the bell life is generally about 2 years, small clock about 1.5 years. The use of tungsten carbide technology, the life of small and small bell than the original surfacing carbide, small bell life has greatly improved, large, small clock life of more than 4 years.

4 blast furnace roof drain valve transformation Blast furnace exhaust valve is an important blast furnace equipment, with the blast furnace smelting The increase of the strength and the increase of the pressure of the furnace, the wear of the relief valve is exacerbated. The original release valve is used wear-resistant alloy contact surface, the use of ineffective, life only about three months. For a long time, the damage of the bleed valve has become the main reason for the blast furnace equipment, wind furnace blast furnace equipment, so the high rate of wind. In the release valve on the use of infiltration tungsten carbide technology, bonnet, seat contact surface to tungsten carbide material, increasing the valve seat contact surface wear resistance, the life of the relief valve has been greatly improved, its life up to 2 years, greatly reducing the blast furnace equipment offwind rate.

Reconstruction of Fire Pipe in Blast Furnace Air Intake System Another area of ​​successful application of tungsten carbide technology in the ironmaking plant is the rear end of the fire tube in the blast furnace inlet system. In the past, the end of the fire tube and the elbow at the junction of ordinary steel material, at the time the wind temperature and wind pressure can also be used in the case of small, but with the blast furnace air temperature and air volume, wind pressure, Tube damage and leakage of air problems, effectively extending the life of the fire pipe, reducing the blast furnace winds.

6 concluding remarks Tungsten carbide technology in the extensive application of ironmaking blast furnace equipment, so that the technical and economic indicators of ironmaking blast furnace has been effectively improved; it greatly reduces the cost of iron, and achieved significant benefits to promote the application of a larger value.

"Seabed rich cobalt crust", another can be collected thousands of years of treasure

After the release of the sailing order by Li Jinfa, deputy director of the China Geological Survey, the "Ocean No. 6" ship slowly departed from the wharf and went to the Pacific Ocean to open the China Geological Survey's annual deep sea geological voyage and the Chinese Ocean 41B voyage. In this expedition, "Ocean VI" will continue to fulfill the China Ocean Association and the International Seabed Authority signed the "exploration contract" international obligations to carry out contract area resource exploration and environmental assessment. This is the China Ocean Mineral Resources Research and Development Association and the International Seabed Authority signed an international seabed cobalt-rich crust mining exploration contract, the fourth time in accordance with the requirements of our contract obligations.

Submarine cobalt-rich crust is followed by combustible ice, China's marine geologists are opening another "can be collected thousands of years of treasure." Cobalt-rich crust It is considered to be the least recognized mineral field, mainly refers to the attached sea slope, rich in cobalt, titanium, nickel, platinum and other metal submarine minerals. These metals, widely used in high-tech industries, the national economy, the whole social development has a very important strategic significance. Such as cobalt is the defense industry and the aerospace industry in the development of essential metals.

In 2014, China Ocean Mineral Resources Research and Development Association and the International Seabed Authority signed an international seabed cobalt-rich crust mining exploration contract. This is the second in 2001 in the northeastern Pacific Ocean to obtain 75,000 square kilometers of polymetallic nodule mining area, in 2011 in the southwest Indian Ocean to obtain 10,000 square kilometers of polymetallic sulphide mining area, China's third with exclusive exploration and priority mining rights of the rich Cobalt crust mining area.

"Ocean 6" this is the fourth time to fulfill the contract obligations, which is for our country in the national jurisdiction outside the international seabed to find strategic resources and carry out a strategic work. The "Ocean VI", which performs the oceanic expedition, will use advanced survey equipment to carry out the "hippocampus" (ROV) survey, multi-beam measurement, shallow stratigraphic profile, columnar sampling (gravity sampling or piston sampling), shallow Sampling, box sampling, multi-tube sampling, submarine camera, temperature and salt measurement, anchor observation, biospheric trawl, gravity measurement and other investigations.

China and the International Seabed Authority signed the contract mine is located in the Northwest Pacific seamounts, an area of ​​3,000 square kilometers, from 150 20 square kilometers of the block and limited to the length of 550 km, the width of 550 km square range. According to the contract, since the signing of the contract within 15 years, China will carry out in the region resource evaluation, environmental investigation, mining and electromechanical system development and testing work, to fulfill the training of scientific and technological personnel in developing countries obligations. In addition to exploration of cobalt-rich crust mining area, "Ocean No. 6" the voyage also shoulder in the Western Pacific Ocean to carry out deep-sea geological survey, the total range of about 22,000 km, which lasted 240 days, plans to return to Guangzhou in February 2018.

This is a total of China Geological Survey, Guangzhou Ocean Geological Survey, Qingdao Institute of Marine Geology, the State Oceanic Administration Second Marine Research Institute, the First Ocean Research Institute, the Third Ocean Research Institute, the National Oceanic Information Center, China Minmetals Changsha Mine Research Institute Co., Ltd., Changsha Mining and Metallurgy Research Institute Co., Ltd., Shanghai Jiaotong University, Chinese Academy of Sciences Institute of Acoustics Donghai Station, Sun Yat-sen University, China University of Geosciences (Beijing), Nanjing Information Engineering University, Hangzhou University of Electronic Science and Technology The The voyage of about 218 people will be the "Ocean No. 6" to carry out the most scientific expedition and the largest number of navigation units.

Study on the Most Water Solubilizing Capacity in W/O Microemulsion

Abstract : The most water solubilizing capacity in microemulsion and influencing factors were studied in this paper. Using span80 and Tween80 as complicated surfactant and using octane as oil phase , Microemulsion was prepared with the action of the ultrasonic. The con2 ductance of microemulsion was measured with the conductance apparatus. Then the graph by ploting with the Original lab software was gained and the most water solubilizing capacity in the breakpoint of the curve was confirmed. There were two important factors that affect2 ed the most water solubilizing capacity : HLB and the concentration of surfactant. By studying the factors , the better result was gained.

Key words : Microemulsion ; Conductance ; The most water solubilizing capacity