Borates have a wealth of uses in metallurgy and gold refinement. Aside from specialized uses such as the production of super strong magnets, borates:
Use of borates in metallurgy begins at the beginning—with the mining process itself. In copper mining, 20 Mule Team® Borax ammonium pentaborate solutions are used to stabilize blasting holes.
In the production of steel and non-ferrous metals, borates act as a flux during smelting. In this capacity, they are used to dissolve metallic oxide impurities, which are then removed with the slag. Borates are also used as a cover flux, to provide a protective barrier against air oxidation. Optibor® and 20 Mule Team Borax potassium pentaborate is used in fluxes for stainless steel or various non-ferrous metals to avoid the glare that is associated with sodium borate. In the refinement of copper, copper alloys, and precious metals, potassium pentaborate can be used as an alternative to fluorine-containing flux compounds, thus helping to reduce fluorine emissions.
In electroplating—including the electroplating of printed circuits—Optibor and fluoboric acids are used in plating solutions, electrolyte solutions, and as an intermediary.
As in metal refinement, in silver soldering, brazing, or welding, potassium pentaborate is used alone or in a mixture with other materials to create a flux that melts and dissolves oxide impurities on the metal surfaces to be joined. Almost all dry paste welding and brazing fluxes contain borates, to protect the surface of the metal against oxidation, act as a solvent in dissolving the metal oxides surrounding the areas to be joined, and serve as a detergent, removing oxides, grease, and other foreign matter.
Ferroboron is used in the production of bonded magnets and permanent magnet materials made with earth-iron alloys. And boron-containing, amorphous metal alloys are used to produce soft magnetic cores that can reduce energy loss in electrical transformers by up to 85%.
Borates readily associate with metallic oxide contaminants at a sufficiently low temperature to minimize the loss of precious metal and reduce wear and tear on melting equipment. In gold refinement, Dehybor® anhydrous borax is used in flux formulations to dissolve metal oxides and as a flux in gold assaying. The addition of Dehybor to the smelt is generally 10-50% of total smelt weight, depending on the process. The borax contribution to flux composition can be up to 60% of total flux weight but is typically around 30-40%.
Borates are also used to facilitate the attack of gold ore at a lower temperature and to make the slag more fluid at the furnace operating temperature, thus reducing viscosity. The benefits of Dehybor in gold refining are numerous:
Furthermore, the product’s formation, purity, and consistent granulometry make it the ideal product for preventing “spit and crackle” problems and facilitating the proper melt.
Most steel slags form hard, rock-like materials upon cooling, whereas others (especially those from the production of stainless steel) form dusty powders. These dusty slags can be prevented by adding anhydrous borax, creating a βC2S polymorph form that results in a stable, rock-like material. Benefits include less slag dust, easier handling of slag, reduction in regulatory oversight and improvement in community relations thanks to improved housekeeping practices, and revenue from sale able slag as well as savings on landfill taxes, disposal costs, and treatment costs. For more information, download the brochure Borates in Steel Slag Stabilization (English). or (Chinese / 中文)
Recycling and recovery of metals such as brass, bronze, copper, lead, zinc, and aluminum can come from scrap or from slag that is left over from a primary smelting operation. The production of a product as pure as primary metal requires the removal of all oxides and extraneous impurities. Borates help by acting as fluxes during melting, combining with metallic oxides at relatively low temperatures to bring them to the surface of the melt as a slag that can be decanted or skimmed off.
In smelting of non-ferrous scrap, anhydrous borates such as Dehybor help to avoid the puffing and intumescence (with possible steam explosions) that can occur when hydrated borates are heated vigorously. Dehybor forms an excellent liquid flux for most bronzes, brasses, and similar alloys and serves as a scavenger to dissolve and carry out oxides, dirt, and sand, which so often contaminate non-ferrous scrap.
In the recovery of nickel, Optibor, 20 Mule Team Borax boric oxide, and Dehybor are used to maintain the neutral pH conditions that are necessary when dissolving impure nickel anodes. Borates are also used in the process of preparing bauxite ore for aluminum, as well as in refining gold and silver. In the latter, Dehybor readily associates with metallic oxide contaminants at a low enough temperature to minimize the loss of precious metal and to increase the longevity of the melting equipment.
In lead recycling and recovery, as with other metals, borates provide value in several ways:
For more information about metals recovery and lead recycling using borates, download Borates in Lead Recycling (PDF).
These 20 Mule Team Borax products are developed for use in metallurgy.
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