A digital refractometer is an instrument used to measure the refractive index of a substance. It works by shining a beam of light through a sample and measuring the angle at which the light is bent. The refractive index is then calculated based on this angle and the properties of the material being measured. Digital refractometers are commonly used in the food and beverage industry to measure the sugar content of liquids such as fruit juices and wine. They are also used in the automotive and chemical industries to measure the concentration of various fluids. Digital refractometers offer the advantage of being more accurate and easier to read than traditional analog refractometers. Digital Refractometer,Auto Digital Refractometer,Auto Portable Refractometer,Portable Automatic Refractometer Lachoi Scientific Instrument (Shaoxing) Co., Ltd. , https://www.lachoinst.com
Humans have long used zinc-containing copper alloys. China's earliest control of zinc smelting technology, the Ming Dynasty "Heavenly Creations," said zinc is lanthanum lead. Europeans received zinc in the 5th century BC. In the 16th-18th century, Chinese zinc was introduced into Europe and was known as tuwtenagne with a purity of 98%. Brestol began production of zinc in 1738 in the United Kingdom. In 1746, the German chemist SAMerggraf calcined a heterogeneous mineral (H2Zn2SiO5) and charcoal to produce metallic zinc. In the 19th century, zinc smelting was developed in France and Belgium.
â– The nature of zinc
Zinc is brittle at room temperature and softens when heated to 100-150°C. However, it becomes brittle after 200°C and is easily broken into powder. Zinc is an active metal and forms a dense basic zinc carbonate film on the surface in air at room temperature, preventing the continued oxidation of zinc. When heated to 225°C, zinc oxidizes intensely and burns blue-green flames. When heated, zinc reacts with fluorine, chlorine, bromine and sulfur to form a compound. Zinc is a negative potential metal, easily soluble in acid, but also easy to replace certain metals from the solution, such as gold, silver, copper, cadmium and so on. Important compounds are zinc oxide, zinc sulfate, zinc chloride.
â– Resources for zinc
There are many types of zinc in the natural world. Common minerals are zinc sphalerite, wurtzite, smithsonite, heteropolar ore, wollastonite and hydrozinc. The world reserves of 2.4 billion tons of zinc metal, output increased year by year, 1980 production of 6.14 million tons. China's zinc reserves are 33 million tons, and in 1993 it was 859,900 tons.
â– Preparation of zinc
The zinc concentrates produced by the floatation of lead-zinc sulfide ore generally have the following composition: zinc is about 50%, sulfur is about 30%, iron is 5-14%, and also contains small amounts of lead, cadmium, copper and precious metals, and trace amounts of indium and antimony. , é•“, é“Š and other scattered metals. Zinc sulphide concentrate zinc smelting methods are wet and fire. The approximate proportions of zinc produced by various methods of smelting zinc in the 1970s were: wet method zincification 74% and pyrometallurgical zinc method 26% (including vertical tank method 5.6%, horizontal tank method 2.2%, blast method 11.4%, electric heating Method 6.8%).
â– Use of zinc
Zinc is widely used in the manufacture of various alloys such as brass, cupronickel, and bronze. Brass with a zinc content of less than 40% is of the greatest value. The addition of tin, nickel, manganese, iron, tungsten, lead, etc. to brass can change its physical properties. Therefore, this type of alloy is called special brass. Another use of zinc is galvanization. It is also used in the manufacture of dry batteries. Since zinc can be filled with fine parts inside the mold during casting in the foundry industry, it is often used as a raw material for precision castings in the automotive industry. Zinc compounds are available. In the textile industry and medicine, rubber. It manufactures paints, pigments, dyes, etc., produces insecticides in agriculture, and also manufactures microcrystalline zinc plates for use in fax fabs and die casting alloys.
Preparation of zinc and others
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