Acid Ferric Sulfate

Sulfide minerals can also be oxidized by the acidic ferric sulfate solutions produced (as shown in the last two equations), with the formation of elemental sulfur ... 

The bacterial leaching of uranium minerals is complex. This is because of the fact that uranium minerals are not sulfides and are not, therefore, directly attacked by the bacteria. However, the uranium sources usually have a substantial pyrite content which can be bac-terially oxidized to give an acidic ferric sulfate solution which is an effective leaching medium for uranium minerals. The reactions involved in the system can be shown in a simplified form as ... 

Silver is tarnished by sulfur, sulfur dioxide, and mercury. It also is attacked by ozone, hydrogen peroxide, chromic acid, ferric sulfate, and permanganate solutions. 

Figure 30 Schematic polarization curves illustrating the origins of the ability of the oxalic etch test and acid ferric sulfate test to differentiate sensitized (represented by the Fe-lOCr-lONi) from unsensitized (represented by the Fe-18Cr-10Ni) material.

Figure 38 Comparison of data from SL-EPR, acid ferric sulfate, and oxalic acid etch test for seven separate heats of Type 304 and 304L stainless steel. Note that for low levels of sensitization, the SL-EPR can quantitatively distinguish among degrees of sensitization. At higher levels, the coupon exposure tests are more discriminating. (From Ref. 32.)...

Acid Calcium Phosphate, 68, (Sl)9, (S2)4 Acid Ferric Sulfate TS, 852 Acid Hydrolysates of Proteins, 13, (Sl)l Acid-Hydrolyzed Milk Protein, 13, (Sl)l Acid-Hydrolyzed Proteins, 13, (Sl)l Acidified Sodium Chlorite Solutions, (S3)3... 

Between 45 and 90°C, the reaction of cubanite with acidic ferric sulfate solutions followed linear kinetics, indicating that the rate-controlling step was some reaction occurring on the surface of the cubanite. The dissolution rate increased with ferric ion concentration and decreased with increasing concentration of sulfuric acid and ferrous sulfate. The naturally slow reaction was accelerated with the addition of NaCl or HCl. The addition of salt in a dump leaching operation would be a relatively easy and cheap procedure to attain increased reaction rates. 

Acid ferric sulfate test (Streicher test) 50 wt% H2S04 + 25 g/L ferric sulfate 120 h exposure to boiling solution Weight loss per unit area +0.7 to+0.9 1. Chromium-depleted areas 2. Sigma phase in some alloys... 

Chemicals used in the quality control analyses in the shieided glove box (SGB) and ventilation hoods of the Quality Control Laboratory involve small (less than a liter) quantities of some acidic and basic chemicals, including ammonium thiocyanate, stannous chloride, sulfuric, nitric, and hydrochloric acids, ferric sulfate, carrier solutions, ethyl acetate, sodium nitrite, chloroform, sodium hydroxide, and potassium iodide. Material Safety Data Sheets for any processes implemented in the HCF are reviewed in accordance with the SNL ES H Manual to identify any carcinogens or other hazardous materials. Operations in the SGB for preparation of various Mo-99 product dilution samples would require a small bulk supply of sodium hydroxide (0.1 N NaOH). Quality control analysis sample preparation operations require small bulk supplies of the above chemicals. Workers performing quaiify control analysis use chemical handling procedures as required by the Sandia ES H Manual. 

Sulfuric acid + ferric sulfate Sulfuric acid + methanol Sulfuric acid + nitric acid Sulfurous acid Water + starch + sulfur dioxide... 

Generally, evaluation in the 50 % sulfuric acid ferric sulfate test is by weight-loss. However, on alloys C and C-276 the relatively low chromium content of about 15 % (i.e., 3 % less than in Type 304 steel) results in a somewhat high rate of general corrosion that tends to mask low rates of intergranular attack. Therefore, to establish evidence of intergranular attack, microscopic examination is recommended in ASTM G 28 to supplement the corrosion rate (weight-loss) data. The newer C-type alloys (Table 1) have 20 to 23 % chromium, and therefore do not pose this problem. 

Information on "acceptable and nonacceptable corrosion test results has been given for the two EPR tests in the section above on these tests. Acceptable etch structures (step, and in some cases, dual) are also identified for the oxalic acid etch test. The absence of fissures in bends after certain copper sulfate tests is considered an indication of acceptable results. However, in the case of weight-loss tests (nitric acid, ferric sulfate, and certain copper sulfate tests) the standard ASTM test methods merely show how corrosion rates are calculated without identification of rates which are evidence of the onset of susceptibihty to intergranular attack. 

Other interesting potential FTPAS kinetic studies that we have planned include measurement of the rate of leaching of copper ions from suspensions of highly colored copper sulfide ores in acidic ferric sulfate solutions and an infrared FTPAS study of the epoxidation of ethylene on a solid silver-silver oxide catalyst. 

Acid ferric sulfate test. It is described in ASTM designation A262-68. 

Sulfuric acid, Toluenesulfonic acid, Phosphonic acid. Hydrochloric acid. Ferric sulfate hydrate. Methyl thiosulphate, Hydroiodic acid. Aluminium trichloride, Niobic acid Alkyl benzene sulfonic acid... 

The chromate-free treatment based on the sulfuric acid-ferric sulfate etch provided an improved joint strength compared with dichromate-sulfuric acid etching, alkaline etching, or mechanical abrasion. This increase is associated with the porous oxide layer formed, hut it depends on the adhesive nature used. The joints with Al—Cu—Mg alloy substrates generally presented higher adhesive strength values than those with pure aluminum adherends because of the selective etching of other elements and inter-metallic compounds, which have different electrochemical potential. 

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