Reagents and Chemicals

Cyanide Destruction Hypochlorite / Chlorine

In the Cyanide Destruction by Hypochlorite reaction, the pH has a strong inverse effect on the ORP. Thus, wastewater treatment facilities must closely control the pH to achieve consistent ORP control, especially if they use hypochlorite as the oxidizing agent. Adding hypochlorite raises the pH, which, if unchecked, lowers the ORP. calling for additional hypochlorite. Controlling the pH at a setting above the pH level where hypochlorite has an influence and separating the ORP…

Alkaline Chlorine-Hypochlorite Oxidation: Chlorine was used for cyanide destruction in the early

←   Read The Full Metallurgy Article

By | 2017-03-19T08:37:04+00:00 March 13th, 2017|Categories: Cyanide Leaching, Reagents and Chemicals|Comments Off on Cyanide Destruction Hypochlorite / Chlorine

Rotary Kiln Maintenance

Rotary Kiln Alignment

The continuity of operation of a lime sludge kiln requires strict maintenance control. The rotary kiln is among the largest type of moving machines made and is subjected to extreme temperatures, power failures, atmospheric conditions, varying loads, and other operating conditions which affect its wear and alignment. It should be erected under the supervision of an experienced erecting engineer.

Even though great care has been taken in the design and the construction of the concrete piers, in some cases settling or tipping of the foundation can occur, throwing the carrying mechanisms, bases, and

←   Read The Full Metallurgy Article

By | 2017-03-17T19:12:09+00:00 November 28th, 2016|Categories: Equipment, Reagents and Chemicals|Tags: , , |Comments Off on Rotary Kiln Maintenance

Rotary Lime Kiln Operation

Precipitated calcium carbonate, commonly called lime sludge or lime mud, is produced when sulphate green liquor is causticized with lime. For many years this lime sludge was considered a waste product and was dumped into rivers or waste ponds, or used for fill around the plants. Large quantities of new lime were purchased from commercial producers to replace that lost in the sludge waste.

A number of paper manufacturers soon became aware of the savings that could be achieved by recovering the lime. Beginning in the ’20’s, efforts were directed toward lime recovery installations. Today, a

←   Read The Full Metallurgy Article

By | 2017-03-17T19:12:10+00:00 November 28th, 2016|Categories: Equipment, Reagents and Chemicals|Tags: , , |Comments Off on Rotary Lime Kiln Operation

How pH Affects Cyanide Decomposition & Use Alkalinity to Preserve Cyanide

Since acidity of the ore causes decomposition of the cyanide, an obvious method of reducing the loss is to add alkali in some form. Before doing this, the free sulphuric acid and soluble salts may be removed by leaching with water, and then a solution of caustic soda or lime is run on to the ore, and after standing for some time is drained off and followed by the cyanide solution. The insoluble basic salts are thus converted into ferric hydrate and soluble sulphates:

Fe2O3. 2SO3 + 4NaOH + OH2 = Fe2(OH)6 + 2Na2SO4
2Fe2O3. SO3 + 4NaOH + 4. OH2 = 2Fe2(OH)6 + 2Na2SO4

Leaching with water then removes

←   Read The Full Metallurgy Article

By | 2017-03-17T19:14:33+00:00 November 2nd, 2016|Categories: Gold Refining, Reagents and Chemicals|Comments Off on How pH Affects Cyanide Decomposition & Use Alkalinity to Preserve Cyanide

How to Prepare and Storage of Cyanide Solution

The cyanide is usually dissolved in a little water before being added to the stock solution, as the amount of KCy present is more easily determined in a strong solution than in any other form. A special dissolving vat of small size is often provided and is placed at a higher level than the large vats used for the storage of the stock solution. High grade cyanide is now largely used containing 98 to 99 per cent, of KCy. Sodium cyanide is also used, and this, calculated as potassium cyanide, contains 125 to 130 per cent, of available KCy. The contents of these boxes are broken into lumps and

←   Read The Full Metallurgy Article

By | 2017-03-17T19:14:41+00:00 November 2nd, 2016|Categories: Cyanide Leaching, Reagents and Chemicals|Comments Off on How to Prepare and Storage of Cyanide Solution

Gold Chloride

Gold Monochloride or Aurous Gold Chloride “AuCl” is a salt is prepared by heating the trichloride to 185° in air for twelve hours. It is non-volatile and unaltered at ordinary temperatures and pressure by dry air, even when exposed to light, but begins to decompose at temperatures above 160°, and the decomposition is complete if it is heated at 175° to 180° for six days, or at 250° for one hour. Its density is 7.4. Water converts aurous chloride into a mixture of gold and gold trichloride. It is a citron-yellow amorphous powder.

Auro Aurichloride

Au2Cl4 is a dark red compound

←   Read The Full Metallurgy Article

By | 2017-03-17T19:16:23+00:00 October 24th, 2016|Categories: Gold Extraction, Laboratory Procedures, Mineralogy, Reagents and Chemicals|Tags: |Comments Off on Gold Chloride

Flotation Conditioning

Flotation Conditioning is often necessary as it is not sufficient merely to make the addition of the various reagents to the pulp and then to proceed with flotation. Intimate admixture is essential in order not only to bring about their even dissemination throughout the pulp but also to ensure that the millions of particles of varying nature shall each receive its proper degree of treatment. Moreover, sufficient air-bell contacts must be provided to promote flocculation of the minerals that it is desired to float. In general, opportunity must be afforded for the various complex

←   Read The Full Metallurgy Article

By | 2017-03-17T19:18:35+00:00 October 16th, 2016|Categories: Flotation, Reagents and Chemicals|Comments Off on Flotation Conditioning

Assay gold and silver in cyanide solutions

In the assay of gold and silver in cyanide solutions the degree of accuracy and the speed desired are the governing factors in the choice of methods used and the quantity of solution taken for the determination.

Evaporation {Litharge) Method

To an evaporating dish add about 50 grams litharge and 146 to 292 cc cyanide solution. Evaporate to dryness, adding about 10 grams litharge during the evaporation. Scrape out the dried cake, and swab the dish thoroughly with a filter paper moistened with dilute HCl. Flux the cake and paper in a crucible, and cupel the resulting button. This method may be used on either pregnant or barren

←   Read The Full Metallurgy Article

By | 2017-03-18T12:55:05+00:00 September 1st, 2016|Categories: Laboratory Procedures, Reagents and Chemicals|Comments Off on Assay gold and silver in cyanide solutions

Assaying for Zinc in Cyanide Solution

Zinc usually occurs in cyanide solutions as the double cyanide, but under certain conditions, e.g., in dilute solutions, a portion of the zinc may be present as zinc cyanide. It is possible that some may also exist as an alkaline zincate.

Procedure

To 500 cc of solution add 10 cc HCl, 10 cc HNO3, and 8 cc H2SO4. Evaporate on a hot plate until copious fumes of SO3 are evolved. Take down over a flame until 2 to 3 cc remain. Take up with 10 cc water and 5 cc H2SO4, and again evaporate to strong fumes of SO3 and dryness. Care should be taken at this stage to avoid spitting. Cool

←   Read The Full Metallurgy Article

By | 2017-03-18T12:56:03+00:00 September 1st, 2016|Categories: Laboratory Procedures, Reagents and Chemicals|Comments Off on Assaying for Zinc in Cyanide Solution

Ferrocyanide Assay Determination

The most reliable method of determining ferrocyanide in a cyanide solution is to determine the total iron and calculate to ferrocyanide.

Volumetric Method

Procedure

To 200 to 500 cc solution, depending upon the quality of ferrocyanide thought to be present, add 10 cc HCl and 5 cc HNO3, and evaporate to about 50 cc. Add 8 cc H2SO4, and evaporate to strong fumes and almost dryness. Cool, add 5 cc water and 5 cc H2SO4, and again evaporate almost to dryness. Cool, add 50 cc water and 5 cc HCl, and heat to dissolve the soluble salts.

Add 3 grams pure zinc (20 mesh). If arsenic is thought to be present, add 3 cc of 4 per cent

←   Read The Full Metallurgy Article

By | 2017-03-17T19:21:13+00:00 September 1st, 2016|Categories: Laboratory Procedures, Reagents and Chemicals|Comments Off on Ferrocyanide Assay Determination