GB/T 3286.9-2014Method for chemical analysis of limestone and dolomite—Part 9: The determination of carbon dioxide content—The caustic asbestos absorption gravimetric method (English PDF)

1 Scope

This Part of GB/T 3286 specifies the determination of carbon dioxide content through the caustic asbestos absorption gravimetric method.

This Part is applicable to the determination of carbon dioxide content in limestone and dolomite, and also to the determination of carbon dioxide content in metallurgical lime. The determination range (mass fraction) in limestone and dolomite. carbon dioxide content 30% ~ 50%; the determination range (mass fraction) in metallurgical lime. carbon dioxide content greater than 0.50%.

2 Normative References

The following documents are indispensable to the application of this document. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document.

GB/T 2007.2 General Rules for the Sampling and Sample Preparation of Minerals in Bulk - Manual Method for Sample Preparation

GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods

GB/T 8170 Rules of Rounding off for Numerical Values & Expression and Judgment of Limiting Values

3 Principle

The test portion is decomposed with phosphoric acid, and dry air with carbon dioxide removed is used as the carrier gas. The generated carbon dioxide is absorbed by caustic asbestos. In accordance with the increased mass, calculate the carbon dioxide content.

The moisture generated during the decomposition of the test portion is absorbed by sulfuric acid and magnesium perchlorate, and the hydrogen sulfide generated from the sulfide is absorbed and removed by chromium trioxide sulfuric acid solution.

4 Reagents

4.1 Unless it is otherwise stated, only approved analytically pure reagents and above Grade-3 distilled water complying with the stipulations of GB/T 6682 or equivalent water shall be used in the analysis.

4.3 Caustic asbestos, with a particle size of 0.5 mm ~ 1 mm.

4.4 Anhydrous magnesium perchlorate, with a particle size of 0.5 mm ~ 1 mm; dry in a drying oven at 180 °C for 2 hours, quickly transfer to a desiccator, cool and set aside.

4.5 Anhydrous calcium chloride.

4.6 High-purity calcium carbonate, not lower than 99.99%.

4.7 Dehydrated sulfuric acid. place sulfuric acid (rho = 1.84 g/mL) in a beaker, heat until it emits smoke, and maintain for a while, let it slightly cool, then, carefully place in a desiccator, cool and set aside.

4.8 Phosphoric acid, 1 + 1.

5 Instruments and Devices

The device for measuring carbon dioxide is shown in Figure 1. Description of indexes.

5.1 Rotor flowmeter (1 in Figure 1), 20 mL/min ~ 200 mL/min, used to observe the flow of air as the carrier gas.

5.2 Drying tower (2 in Figure 1). with a capacity of approximately 500 mL, containing soda lime (4.2).

5.3 Drying tower (3 in Figure 1). with a capacity of approximately 500 mL, containing anhydrous calcium chloride (4.5).

5.4 Special-made acid adding tube (4 in Figure 1). with a capacity of 30 mL.

5.5 Special-made connecting tube (5 in Figure 1). use double-hole rubber plugs to connect to the dry tower (5.3) and the special-made acid adding tube (5.4).

5.13 Drying tower (13 in Figure 1). the lower part contains anhydrous calcium chloride (4.5), the upper part contains soda lime (4.2), separated by absorbent cotton in the middle.

5.15 Water flow suction tube (15 in Figure 1), connected to the faucet.

5.16 All parts of the device are connected with rubber hoses of appropriate length as shown in Figure 1, and each device is fixed with corresponding clamps.

5.14 Gas washing bottle (14 in Figure 1), containing water

6 Specimen Preparation

6.1 In accordance with GB/T 2007.2, prepare the specimens.

6.2 The specimens shall be processed until the particle size is less than 0.125 mm.

6.3 Before analysis, the limestone and dolomite specimens shall be dried at 105 °C ~ 110 °C for 2 hours and placed in a desiccator to cool to room temperature.

7 Analysis Steps

8 Calculation and Expression of Analysis Results

9 Allowable Differences

The difference between two independent analysis results within the laboratory and the difference between two laboratory analysis results shall not be greater than the corresponding allowable differences listed in Table 1 […]