ASTM C1318-95

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Designation: C 1318 – 95
Standard Test Method for
Determination of Total Neutralizing Capability and Dissolved
Calcium and Magnesium Oxide in Lime for Flue Gas
Desulfurization (FGD)
This standard is issued under the fixed designation C 1318; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4.2 A sample of lime is titrated with 1N hydrochloric acid,
maintaining a pH of 6 for 30 min. After 30 min, the acid
1.1 This test method covers analysis of magnesian, dolo-
consumption is recorded. The total neutralizing capacity is
mitic and high-calcium limes for total neutralizing capability
calculated from the acid consumption and reported as CaO.
and dissolved major oxides. Dissolved calcium and magnesium
Dissolved magnesium is determined by atomic absorption
are the major species that neutralize acid under the conditions
spectrometry or by EDTA titration and reported as percent
of the test.
dissolved Magnesium Oxide (as MgO).
1.2 The test conditions are chosen to measure the acid-
neutralizing capacity of both calcium hydroxide and magne-
5. Significance and Use
sium hydroxide contained in slaked lime. By controlling the
5.1 There are existing lime-based flue gas desulfurization
neutralization pH at 6, magnesium hydroxide and magnesium
units in operation that require a method to measure the oxides
oxide are titrated in addition to calcium hydroxide fraction.
available for sulfur dioxide absorption. Dissolved magnesium
1.3 This test method also determines the fraction of Mg ions
oxide varies among limes depending on the limestone sources
present in the lime that will dissolve under lime flue gas
++
and calcination conditions.
desulfurization (FGD) conditions. Because the Mg ion alters
FGD performance, it is important to know its concentration.
6. Interferences
1.4 This standard does not purport to address all of the
6.1 Any substance reacting with acid under the conditions
safety concerns, if any, associated with its use. It is the
of the test will contribute to the total oxide and dissolved oxide
responsibility of the user of this standard to establish appro-
values.
priate safety and health practices and determine the applica-
6.2 Magnesium in forms other than MgO, which dissolve
bility of regulatory limitations prior to use.
under test conditions, may affect the dissolved MgO and total
oxide value.
2. Referenced Documents
2.1 ASTM Standards:
7. Apparatus
C 25 Test Methods for Chemical Analysis of Limestone,
7.1 Digital Readout pH Meter, with combination electrode
Quicklime, and Hydrated Lime
readable to 0.01 pH units, or an autotitrator with an automatic
C 50 Practice for Sampling, Inspection, Packing and Mark-
2 temperature compensator capable of titrating to a preset
ing of Lime and Limestone Products
endpoint (Note 1).
C 51 Terminology Relating to Lime and Limestone (as
Used by the Industry)
NOTE 1—Use of an automatic titrator is recommended.
7.2 Stirrers and Stir Bars.
3. Terminology
7.3 Atomic Absorption Spectrometer, if not using EDTA
3.1 Definitions—Unless otherwise specified, for definitions
titration.
of terms used in these test methods refer to Terminology C 51.
7.4 Filtering Funnel, Type AE glass fiber paper, volumetric
flasks (size as needed), 500 mL volumetric flasks, and various
4. Summary of Test Method
Class A pipettes.
4.1 Lime is slaked by boiling and is reacted with acid at a
pH and residence time similar to those found in full-scale FGD
8. Reagents
reaction tanks.
8.1 1.0 Normal Hydrochloric Acid, standardize using pro-
cedures in Test Methods C 25, Section 28.
This test method is under the jurisdiction of ASTM Committee C-7 on Lime
and is the direct responsibility of Subcommittee C07.05 on Chemical Tests.
Current edition approved Nov. 10, 1995. Published February 1996.
Annual Book of ASTM Standards, Vol 04.01.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 1318
8.2 Distilled Water,CO free. 10.3.2.3 Repeat 10.3.2 and determine the total dissolved
8.3 Calcium and Magnesium Standard Solutions (commer- oxides according to Test Methods C 25, Paragraph 31.6.5.
cially available or use methods in Test Methods C 25, Section Record mL of EDTA required for this titration.
31).
8.4 EDTA Standard Solution (0.4 %), standardize according 11. Calculation of Results
to Test Methods C 25, Section 31.5, Standardization of EDTA.
11.1 Percent Total Neutralizing Capability (TNC):
9. Sample Preparation A 3 B 3 C
% TNC ~as CaO! 5 (1)
W
9.1 The sampling and grinding of any lime sample shall be
carried out as rapidly as possible, so that the absorption of
where:
moisture and carbon dioxide is held to a minimum.
A 5 mL HCl used in 10.2.3,
9.2 The sample as received at the laboratory shall be
B 5 normality HCl,
thoroughly mixed and a representative sample with minimum
C 5 chemical factor 5 2.804 (mequi of CaO/10), and
weight of 100 g shall
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