Although it has long been known that activated carbon is a good adsorbent for gold cyanide, the early method of recovering gold from gold-loaded charcoal is to burn off the gold-loaded charcoal and then smelt the gold from the ash. The activated carbon can only be used once and the cost is high. After World War II, the United States due to the excess of activated carbon, low prices, but also of interest to people recovering gold and silver from the cyanide solution with activated carbon. Since then, the US Bureau of Mines has been working on the study of gold-carbon desorption methods. In 1950, a method for desorbing gold from gold-loaded carbon with an alkaline sodium sulphide solution was published, which had little effect on the silver on the gold-loaded charcoal. In 1952 Zade published a method for desorbing gold-loaded carbon with a hot sodium hydroxide-sodium cyanide mixed solution, namely Zhadra desorption. The desorption method is to use a 1% sodium hydroxide solution and a 0.1% sodium cyanide mixed solution to heat to 90-95 ° C, and pass through the gold-bearing carbon layer at a certain speed, and the gold and silver on the gold-loaded charcoal are desorbed and enter. In solution. The result of the laboratory is desorption for 4-6 hours, and the desorption rate of gold and silver is over 90%. However, in actual production, it usually takes 50 to 70 hours to achieve a high desorption rate. Despite the long desorption time, the Zade process makes it possible to reuse activated carbon, which greatly reduces the operating cost of gold mine heap leaching operations.

The Die Castings that are created in this process can vary greatly in size and weight, ranging from a couple ounces to 100 pounds. One common application of die cast parts are housings - thin-walled enclosures, often requiring many ribs and bosses on the interior. Metal housings for a variety of appliances and equipment are often die cast. Several automobile components are also manufactured using Die Casting, including pistons, cylinder heads, and engine blocks. Other common die cast parts include propellers, gears, bushings, pumps, and Valves.


Die casting is a manufacturing process that can produce geometrically complex metal parts through the use of reusable molds, called dies. The die casting process involves the use of a furnace, metal, die casting machine, and die. The metal, typically a non-ferrous alloy such as aluminum or zinc, is melted in the furnace and then injected into the dies in the die casting machine. There are two main types of die casting machines - hot chamber machines (used for alloys with low melting temperatures, such as zinc) and cold chamber machines (used for alloys with high melting temperatures, such as aluminum). The differences between these machines will be detailed in the sections on equipment and tooling. However, in both machines, after the molten metal is injected into the dies, it rapidly cools and solidifies into the final part, called the casting. The steps in this process are described in greater detail in the next section.


Die cast parts can vary greatly in size and therefore require these measures to cover a very large range. As a result, die casting machines are designed to each accommodate a small range of this larger spectrum of values. Sample specifications for several different hot chamber and cold chamber die casting machines are given below.


Type Clamp force (ton) Max. shot volume (oz.) Clamp stroke (in.) Min. mold thickness (in.) Platen size (in.)
Hot chamber 100 74 11.8 5.9 25 x 24
Hot chamber 200 116 15.8 9.8 29 x 29
Hot chamber 400 254 21.7 11.8 38 x 38
Cold chamber 100 35 11.8 5.9 23 x 23
Cold chamber 400 166 21.7 11.8 38 x 38
Cold chamber 800 395 30 15.8 55 x 55
Cold chamber 1600 1058 39.4 19.7 74 x 79
Cold chamber 2000 1517 51.2 25.6 83 x 83

The selection of a material for die casting is based upon several factors including the density, melting point, strength, corrosion resistance, and cost. The material may also affect the part design. For example, the use of zinc, which is a highly ductile metal, can allow for thinner walls and a better surface finish than many other alloys. The material not only determines the properties of the final casting, but also impacts the machine and tooling. Materials with low melting temperatures, such as zinc alloys, can be die cast in a hot chamber machine. However, materials with a higher melting temperature, such as aluminum and copper alloys, require the use of cold chamber machine. The melting temperature also affects the tooling, as a higher temperature will have a greater adverse effect on the life of the dies.

Materials Properties
Aluminum alloys ·Low density
       Â·Good corrosion resistance
       Â·High thermal and electrical conductivity
       Â·High dimensional stability
       Â·Relatively easy to cast
     Â·Requires use of a cold chamber machine
Copper alloys ·High strength and toughness
       Â·High corrosion and wear resistance
       Â·High dimensional stability
       Â·Highest cost
       Â·Low die life due to high melting temperature
     Â·Requires use of a cold chamber machine
Zinc alloys ·High density
       Â·High ductility
       Â·Good impact strength
       Â·Excellent surface smoothness allowing for painting or plating
       Â·Requires such coating due to susceptibility to corrosion
       Â·Easiest to cast
       Â·Can form very thin walls
       Â·Long die life due to low melting point
     Â·Use of a hot chamber machine
Advantages: ·Can produce large parts
       Â·Can form complex shapes
       Â·High strength parts
       Â·Very good surface finish and accuracy
       Â·High production rate
       Â·Low labor cost
     Â·Scrap can be recycled


Die Casting

Die Casting,Aluminum Die Casting,Die Casting Parts,Zinc Die Casting

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