Tungsten Copper Content Test Method

Tungsten Copper Content Test Method

Dissolved the sulfuric acid and ammonium sulfate, added a solution of potassium iodide in the weak medium, and then reduction Cu2+ to Cu+ precipitation equivalents iodine.
Starch solution as indicator, the copper content was measured by the volume of standard solution of sodium thiosulfate titration. This method is applicable to the determination of copper content in the range: 15% to 45%.

Tungsten Copper Content Test Method Steps

Reagent Preparation
1, sulfuric acid (p1.84g / ml)
2, ammonium sulfate, a solid
3, acetic acid (36%)
4, sodium fluoride solution (20g / L)
5, ammonium hydroxide solution (1 + 1)
6, potassium iodide solution (200g / L)
7, ammonium thiocyanate solution (200g / L)
8, sodium thiosulfate standard solution preparation and calibration 0.025mol
8.1 Preparation
Weigh 6.2g sodium cooled boiled water soluble, 0.2g of anhydrous sodium carbonate, dissolved in diluted boiled and cooled water to 1000ml, shake.
8.2 Calibration
Accurately weigh 0.0500g copper (99.95%) in 250ml triangular beaker, add 10ml of nitric acid (1 + 1) is heated to dissolve, divisible nitrogen oxides, evaporated to near dryness, cooling, add about 20ml of water.
Quality standard solution of sodium thiosulfate considerable copper according to equation (1):
C = m / v (1)
The above calculation formula:
C --- fairly standard solution of sodium thiosulfate copper, g / ml;
m --- copper weighed mass, g;
V --- calibration standard solution of sodium thiosulfate, ml.
9, starch solution (5g / L)

Analysis Steps

1. Sample
Table 1. Weigh the sample in triplicate, to the nearest 0.0001g.
Table 1 Sample Volume

Copper Content (%)

Sample Volume (%)

15.00~30.00

0.2000

>30.00~45.00

0.1000

2. Test
2.1 The sample was placed in 250ml triangular cup, add 5ml of sulfuric acid, 3g ammonium sulfate, no neck cover small funnel, dissolved by heating and then cooled to 50 ~ 80 ℃, add water about 10ml, shake to dissolve the viscous colloid.
2.2 Plus 10ml of sodium fluoride solution with ammonium hydroxide solution and to the copper ammine ions appear blue, and then dropping acid to copper ammonia complex ion disappearance of the blue and excess 3ml, water cooled to room temperature.
2.3 Adding 10ml of potassium iodide solution with sodium thiosulfate solution immediately drops to the standard blue color disappears as the end point.

3. Analyze Results
Percentage of copper in accordance with formula (2):
Cu (%) = (c * v) / mx100% (2)
C --- thiosulfate standard solution of copper equivalent quality, g / ml;
V --- Consumed sodium thiosulfate standard solution, ml;
m --- Sample, g.

4. Allow Poor
The difference between the test results should not exceed allowable difference listed in Table 2
Table 2 Allow Poor

Copper Content (%)

Allow Poor (%)

15.00~30.00

0.20

>30.00~45.00

0.30

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