It is a gray-black metal with metallic luster (body-centered cubic crystal). Melting point 3400 ℃. Boiling point 5555℃. The hardness of tungsten is the hardest among metals. The hardness of the sintered Tungsten Rod is 200~250, and the tungsten rod passed through the rotary hammer is 350~400. Soluble in mixed acid of nitric acid and hydrofluoric acid. Melt with a mixture of sodium hydroxide and sodium carbonate. Slightly soluble in nitric acid, sulfuric acid, aqua regia; insoluble in water, hydrofluoric acid, potassium hydroxide. Tungsten is available in two variants, a and B. At standard temperature and atmospheric pressure, type a is a stable body-centered cubic structure. Type B tungsten can only appear in the presence of oxygen. It is stable below 630 °C, and is converted into a-tungsten above 630 °C, and this process is irreversible. Tungsten is mostly used in the production of cemented carbide and ferrotungsten. Tungsten and chromium, molybdenum and cobalt form heat-resistant and wear-resistant alloys for making tools, metal surface hardening materials, gas turbine blades and combustion tubes, etc. Tungsten and tantalum, niobium, molybdenum, etc. form refractory alloys. Tungsten copper and tungsten silver alloys are used as electrical contact materials. High-density tungsten-nickel-copper alloy is used as a radiation shield. Metal tungsten wires, rods, sheets, etc. are used to make parts of light bulbs, electronic tubes and electrodes for arc welding. Tungsten powder can be sintered into filters of various porosity. FW-1 is used as raw material for large slab and tungsten-rhenium galvanic couple. FW-2 is used for contact alloy, high specific gravity shielding material. FWP-1 is used for plasma sprayed materials. Tungsten Powder,Low Carbon Tungsten Powder,Iron Alloy Tungsten Powder,Cast Tungsten Powder Jiangsu Lucky Metal Materials Co., Ltd. , https://www.luckymetalmoly.com
The conditions for pesticide production access include various aspects such as enterprise layout, production equipment, process technology and products, environmental protection facilities, quality assurance system, safety and health, and personnel qualifications. Among them, the emphasis on environmental protection and safety and health is particularly prominent.
In terms of enterprise layout, access requirements require newly established first-level pesticide production enterprises to be built in industrial clusters that have been approved by the provincial-level and higher-level departments and pass regional environmental impact assessment; newly established secondary pesticide production enterprises must stay away from Crowd gathered area. Before the construction of the factory, the pesticide company shall provide the general plan of the enterprise that has applied for approval. The location of the auxiliary facilities such as the production workshop, raw materials and product storage, fire control, "three wastes" treatment, and public works shall be marked.
In terms of production facilities and process technology, access conditions require the use of energy-saving and environment-friendly equipment. If the chemical synthesis requirements for synthetic drugs involve sulfonation, nitrification, chlorination, diazotization, oxidation, hydrogenation, peroxidation, fluorination, ammoniation, pyrolysis, and high pressure reactions, an automatic control and safety interlock system must be set up. And equipped with reliable alarm facilities. The requirements for environmental protection facilities have also been strengthened in the processing of pesticide formulations. For example, powder preparations and granules are required to have a dust removal system, and a negative pressure isolation space should be provided at the feed inlet.
For the collection and processing of “three wastesâ€, there are more specific rules for access conditions. For example, the ground of a solid waste collection site should be treated with anti-seepage treatment, surrounded by cofferdams, rainproof and fireproof measures; the collection of liquid waste requires separate collection of rainwater, domestic sewage and production sewage; the collection of gaseous waste requires that all are toxic and have The odor, solvent, dust overflow material feed and outlet should be set exhaust devices, and effective treatment of tail gas.
In terms of safety and health, it is required that pesticide production enterprises should be equipped with fire-fighting equipment that conforms to the nature of production, have ventilation and strong exhaust ventilation facilities that meet the production needs, and install eyewashers and emergency shower facilities in the production workshop, and should train relevant emergency personnel. The production, storage and transportation of chemicals shall comply with the regulations and be approved by relevant departments. An emergency rescue plan and command system for accidents shall be established.
According to the introduction of Cao Chengyu, the deputy secretary-general of the China Pesticide Industry Association, from the perspective of comments and feedback, the final "Pesticide Production Entry Conditions" will not be greatly modified in terms of environmental protection, safety and health, etc., and the access conditions will be applicable to the pesticide industry. Energy-saving and emission-reduction and protection of ecological environment and human health play a catalytic role.
Tungsten powder is the main raw material for processing powder metallurgy tungsten products and tungsten alloys. Pure tungsten powder can be made into wire, rod, tube, plate and other processed materials and certain shaped products. Tungsten powder mixed with other metal powders can be made into various tungsten alloys, such as tungsten-molybdenum alloy, tungsten-rhenium alloy, tungsten-copper alloy and high-density tungsten alloy. Another important application of tungsten powder is to make tungsten carbide powder, and then prepare cemented carbide tools, such as turning tools, milling cutters, drills and molds.
The Public Consultation on the “Pesticide Production Approval Requirements†issued by the Ministry of Industry and Information Technology ended on November 10th. The reporter learned from the interview with the China Pesticide Industry Association that participated in the drafting work that as a major focus of the draft, the Content such as safety and safety has been widely recognized by the pesticide industry and will become a "requisite for entry of pesticide production."