R. F. Abernethy and Theodore Christos Bureau of Mines, U. S. Department o f the Interior, Pittsburgh, Pa.
T
HIS is the eighth of a series of reviews on methods of sampling, analyzing, and testing solid and gaseous fuels. The review covers the period from October 1960 through September 1962, and for comparison follows the general format of previous reviews.
SOLID FUELS
This section relates to the methods of sampling, analysis, and testing of coal, coke, and peat reported in the two-year survey. Most of the methods reported are investigations of existing methods to improve reliability and reduce the time required for analysis. Sampling. Tomlinson (8A) reviewed t h e regular methods of sampling and showed t h a t certain general principles are involved. Anderson ( 1 A ) developed charts to determine the fundamental variance characteristics of coal as a function of weight and number of increments collected, number of gross samples analyzed, and quality and amount of analytical work performed. Bertholf ( 2 A ) presented data to show the effect of increased increment weight on the sampling accuracy. It was indicated that the suggested Bertholf-Visman theory was not wholly tenable and that the increment weight affects the number of increments required to produce a specified grosssample accuracy in analysis where the range in sizes is very great. Landry (4A) presented a physical interpretation of statistical variances calculated from coal-sampling data (as applied to ash content), b y relating one of them to a randomly mixed portion and the other to a segregated portion. The weight-consist relations make i t possible to extend the interpretation to sample reduction. Thorough mixing is necessary. Piatkomski (6A) developed statistical methods for choosing the proper weight and number of increments for the ash content of raw coal. He preqented a formula for ash-content variance in increments of different sizes for coal of a given bed, separating this general population by sieving into particle sizes, and using the increment for particles of maximum weight as a sampling unit for all classes. The variance in ash content of the entire production was calculated from the weighted ash content of the several beds.
78 R
ANALYTICAL CHEMISTRY
Murray (5.4) reported methods of sampling and preparing milled peat for moisture determination. He tested an automatic peat sampler for bias in the collection and reduction of the primary sample. Hissink and Kreulen ( 3 A ) reported on the operation of a rotary sample divider for wet coal. A higher accuracy and a saving of time are claimed. Shmachkov (7A) described the construction and operation of several mechanical sampling devices. Wirthwein (9il) reported on a power installation with an automatic device for taking and dividing coal samples. Proximate Analysis. T h e proximate analysis includes moisture, volatile matter, ash, and fixed carbon. T h e moisture, volatile matter, and ash are determined b y specified methods, and t h e fixed carbon is calculated by subtracting the sum of moisture, volatile matter, and ash from 100. MOISTURE.Kreulen (19B) presented data to show that low values for total moisture by oven drying may be due to a reduced temperature caused by the evaporation of water. This difficulty can be eliminated by preliminary air drying. Dvuzhil'naya (10B) compared results by the USSR national standard GOST 6963-55 for oven-drying with the I S 0 proposed toluene distillation method. Results by the oven method were lower in lom-rank coals and higher in high-rank coals than the distillation method. The variations between the two methods for all ranks of coal were within permissible limits of the national standard. The rapid advance of automation is reflected by new methods for the analysis of coal. Lindrum (22B) described a method of measuring the moisture content of brown coal by determining the dielectric constant. With insulated electrodes the top limit of moisture was 50%, but with noninsulated electrodes the method was applicable to coals with moisture values u p to 66%. Tyutyunnikov (d8B) found that permittivity mas a better parameter for the automatic control of moisture than the specific resistivity. The packing density, size analysis, mineral impurities, and temperature have less effect on the permittivity of a coal than on the specific resistivity. Ladner and Stacey @OB) tried several
methods of automatically controlling the moisture content of coal and had only moderate success. Suclear magnetic resonance seems to offer the most promise because of the broad-line resonance with chemically bound hydrogen and the sharp resonance line from hydrogen in water. Dresia, Calamini, and Steinberg (8B) developed a neutron-scattering method for moisture in coke. The volume of coke used for moisture measurement is about 0.4 cu. meter, s o that difficulties of sample collection and preparation are avoided. Ray (26B) concluded from a iurvey of electrical resistance, dielectric, nuclear magnetic resonance, neutron scatter, and thermal-conductivity methods that none will continuously or automatically estimate the moisture content of coal. VOLATILE RIATTER.Factor- affecting the errors in determining the volatile matter were studied 1,Drekopf, Steiner, and Kinzen (7B) They used low-ash coal with knomn minerals to make mixtures for testing in the usual manner. Correction factors w r e derived for the various minerals. Agroskin and Miringof ( I B ) determined the rate of volatile matter evolution at heating ratec of 5' to 140' per minute, respectively) up to 1000" C. The amount of volatile matter !?-as determined by the final decomposition temperature and was independent of the heating rate. The maximum evolution was in the 250' to 400" C. interval. The kinetic rate equation n-as given as log k = l.% - 1928/T; the activation energy n-as qS20 cal. per mole. The speed of volatile component release bv thermal decompo4tinn of coal was studied bv Shapatina ( ZYB 1. Speed of decomposition proceeds a t a variable rate. The volatiles r e l e a d a t 5.50' C. for 0.45 second. 30 ieconcli. nnd 20 minutes n-ere 42, 7 5 , and 9 0 5 of the maximum volatile componeiit- a t the temperature. The British Coke Research A\sociation (RCR.-I) (SB) give; the design of an electric muffle furnace TI ith heating mit using characteristics that d l 1x1 four crucible? Eimultaneou4i for 1 olatile matter in coal and coke. ASH ASD ~ I I S E R A ~ ILA T T E Buiton R. (4R) gave a statiitical procedure for determining the accuracy of the ash determination. GBI, Lisz16, and Varga (ItB)reported
a rapid method for analyzing ash in coal by heating 1.00 gram samples in a n ashing dich for 5 minutes in an oven at 850' C. h determination takes approximately 35 minutes with a n error of 0.4 to 1.0% A portable apparatus for determining moisture and ash in peat \vas reported by Zagorul'ko (SOB). Field analyses agreed with laboratory results nithin 0.lYG. Yusupor (29B) preqented a method and rewlts of the determination of the ash content of coal using a microscope. Comparatke data by chemical and micro~copir methods are given. The method permit< quick determination of the preparation characteri-tics of coals. Chakraxwti. Saha and Sarkar (6B) presented a novel, simple, and rapid method for aqh and moisture in the n e t product for a m-ashery. The method i. haqed on determining three ili the n-eight of the wet neiqht.: sample ( 2 ) veight in water, ( 3 ) and weight in a heavy deniitv liquid. The procedure elinmates drying. crushing, and incinerating and is completed in 10 minutes. Becau-e of automation in coal-cleaning plant. and power station., many worker. are making radiometric studies to determine the ash content of coal. Dahn (6B).Enomoto. l l o r i , and Furuta (1IB) Gorhatvuk et al. ( I S B ) , Irkovckii ( ! 6 BI . Jirkorsky (18B), Mori and $BI and Goroshko and NikanoTaira i? rova ( I 5 B ) uced variou. applications of beta radiation to determine the mineral matter in coal. Drozhzliin Gorbatvuk. and Chashrhinov 19B; Goroshko (14B), and Jirkovsk? (17B) used inctruments b a v d on gamma radiations to measure rapidly the ash content of coal. in proceqs BY definition the ash content of coal is the re-idue remaining after a qample of coal I C burned under specified conditions. The ash content must not be confu-ed with mineral matter, which generally I < e - t i m a t d by calculation with empiiical formulaq or acid extraction method- Loo (2%) stated t h a t the determined a+ for practical calculation. repre-entz 90% of the mineral matter. Ode and Gib-on (26B) found that in low-rank coal' 50 to 95% of the total sulfur naq retained In the determined aqh. re-ulting in a poqitive amount of about 1 to 6 7 Po3 on a dry-coal basis. Fixed carbon and oxygen T-alues, calculated hv difference. would be in error. They qtate that. for accurate work, the SO3 retained in the determined aqh should he deducted. Barker and N o t t iZB) proposed the formula for mineral matter in coke. M M = aqh sulfur - 1,'7 iron, or, if the iron content is unknown, i t be2/3 sulfur. comes AIM = ash
+
+
Leighton and Wald (RIB) established a relation, from a statistical study of a large number of analyses, which appears t o be superior t o the Barker-Mott formula above. When the forms of sulfur are unknown, the formula is MM = ash 0.68 sulfur - 1/7 iron 0.14; if the iron content of the coke is unknown, the formula is M A 1 = ash 0.51 sulfur - 0.21. Ultimate Analysis. CARBOXA N D HYDROGEN.GBl and LBsz16 (SC) reduced the time of analysis for carbon and hydrogen in coal from 2 hours to 30 minutes without sacrificing accuracy b y fitting a platinum catalyst into a Dennqtedt elemental analysis apparatus and heating at 750' to 800' C. in an oxygen atmosphere. The Sheffield high-temperature method for carbon and hydrogen in coal and coke iyas qimplified b y Radmacher and Hoverath (E).A 60-mg. sample is burned a t 1050' C. in an oxygen flow of 50 ml. per minute in an unpacked quartz tube. except for the last third, which i. packed with silver wool and heated to 640' C. to retain sulfur and halogens. A determination requires 25 minutes. Duplicate tests on coal, coke, and brown coal had a standard deviation of = t O . l l % of carbon and =t0.05yo for hydrogen. SULFUR. Fedorovskaya and Zakharora (SC) used lead chromate in the absorption of the sulfur, replacing metallic silver formerly used in this micromethod. GB1. Kovatqits, and Varga (4C) reported on a long and tedious complexometric titration finish of the Eschka method. Herrig (E)used an oxygen bomb to burn the coal and titrated the bomb washings by a rather involved procedure. Magnesia was used by Jenik and Kyvlt (7%') in place of Eichka mixture to absorb the sulfur. The sulfur was recovered from the MgS as HzS by the action of C02. The H2S u-as absorbed in a qolution of AcONa Zn (OAc), and the ZnS m-as titrated with iodine. Szava (IOC) and Zotova (ffC) reported a rapid method by high temperature (1200' C.) combustion and titration of the SOPevolved with iodine. It is claimed t h a t alkali chlorides do not interfere. NITROGEN. A new nonroutine reductive method for nitrogen using metallic lithium was reported b y Radmacher and Hoverath (QC). B y this method, nitrogen in the sample forms a nitride with lithium, which is decomposed with HSP04. The NH3 is distilled from the alkalized KH4-sal t solution and determined as in the usual Kjeldahl procedure. Aranda, Lacal, and Beltran ( I C ) found that selenite was too erratic as an accelerator in the digestion when used for the semimicro-Kjeldahl method.
+
+ +
+
Low or high nitrogen values obtained depended on the amount used. A mixture of 8.7 grams of K2S04and 1.3 grams of HgSOd was satisfactory. OXYGEN.The Unterzaucher method for oxygen in organic materials was modified by Crawford, Glover, and Wood (E)for coal b y refluxing the sample with 10% HC1 in a COZ atmosphere, t o remove some of the mineral matter. The treated coal is pyrolyzed at 900' C. over a platinum-carbon catalyst in a n inert carrier gas. The oxygen compounds are reduced to CO, which reacts with 1206,and the free iodine is determined b y titration. Calorific Value. Schneider ( T D ) used a calorimeter bomb fitted with a window. manometer, and thermoelement to study t h e reactions taking place during a calorific value determination. It was found t h a t all combustibles (including gasoline) burn without explosion. combustion pressures are less t h a n 50 a t m . , for cons t a n t heat release ( 5 to 8 kcal.) t h e maximum pressure and temperature values are higher for materials burning more quickly, and the burning time for coal depends on the volatile matter. An explanation of the formation of coke outside the crucible and methods for its elimination are given. Nijkamp ( 5 0 ) proposed a method to reduce errors in thermometers by using the same section of the stem for all determinations. Temperatures of the inner and outer vessels were regulated with electric heaters. Finally, he proposed to replace the elaborate Regnault-Pfaundler correction formula with the following:
c
=
(Vi
- V?)
[a1
+
0 2
- - - - an-I
+ (a,,*)I-nV'
where V I and 1 1 2 = temperature rise per time interval (30 seconds) in the initial and final periods, respectively, and n = number of time intervals. Moreau ( 4 0 ) claimed a time-saving and accurate procedure for determining the heat of combustion of coal b y using two nearly identical bombs in a constant temperature water bath and gage water of slightly lower temperature. He regulated the weight of sample to give a constant heat release of 7600 cal. and timed the procedure so that the heat gain from and heat loss to the water of the jacket and the heat gain from the stirrer compensate each other. A complete set of formulas for calculating corrections are given. A method of approximating the correction for nitric and sulfuric acids in the heat of combustion of coal was proposed b y Friehmelt and Steinbrecher (JD). Armstrong ( I D ) used a graphical method to determine the cooling correction. It was necessary to take only three temperature readings, thereby freeing the operator for other duties. VOL. 35, NO. 5, APRIL 1963
79 R
It was shown b y Parkhouse (6D) BORON. Kear and Ross (13E) in that stainless steel is inferior to copper their study on the geographic and for calorimeter cans, because of the low stratigraphic distribution of boron in conductivity of heat of the steel. coal developed a new method which is Bisztray-Balku et al. (ZD)conducted similar to that used to determine boron tests to show the close relationship in glass. The results showed a relation between gamma-ray-absorbing capacibetween the boron content and ash ties of various coals and their specific content, calcium in ash, rank of coal gravities, calorific value, and ash conabove subbituminous, structural trends of the area, and the proximity t c hot tents. Even in the development stage this process attains the accuracy of springs. There was no relation with customary calorimetric methods used the boron content and proximate and in laboratories. ultimate analysis, coal type, location in Inorganic Constituents in Coal a n d a single mine, stratigraphic level, and Coal Ash. A rapid method for t h e depositional environment. Hot springs might enrich nearby peat and coal analysis of coal ash was reported b y Bhattacharyya and Banerjee (6E). deposits n i t h boron. Chelatometric methods are used for the GALLICX BND GERMANIUM. c r major constituents evcept SiOe. The b h e k (22E) determined gallium and silica-free filtrate was used for the germanium in coal photometrically determination of iron, aluminum, calafter extraction of the ash prepared at cium, and magneqium by E D T A titra5ooo to 550°. tion a t selective p H values. Phosphorus The spectral method was used by was determined by HC104 extraction, Bronshtein, Sendul'skaya, and Shpirt followed by precipitation as MgNH4P04. (8E) to determine gallium and gerwhich is estimated by chelatometric manium in coal on a single weighed portion, The coal ash is mixed JTith titration. Sulfur was determined by a standard gravimetric method. carbon and NaC1 ( 2 : l : l ) . T o the mixture, 0.1% SnO2 is added as a n Gibson and Ode ( I I E ) and Yamada internal standard and the prepared (25E) evaluated a rapid method for sample is placed on the two carbon analyzing coal ash and related material, based on some of the newer physicoelectrodes of the spectrograph. For concentrations of germanium to 0.003% chemical techniques. Spectrophotothe error is 10 to 12%; for the same metric methods are used to determine SiO2, &03. Fe207, TiO2, and P205; concentrations of gallium the error is chelatometric titrations for CaO and 7.5 to 10%. Ryczek (I9E) has shown that galMgO; and flame photometry for SazO lium and germanium occur chiefly in and K20. Complete analyses in duplithe clarain and durain components of cate can be obtained a t a rate two to the coal. K h e n the coal is burned in a three times that by conventional slightly reducing atmosphere the elemethods. ments are lost as elides; in gasification A spectrographic method mas used by they are lost as sulfides; and in coking -4ngell and Bethell (ZB) to determine in duplicate silicon, aluminum, iron, they remain in the coke. calcium, magnesium and titanium in Losev et al. (16E) conducted eyperieight samples per day. Kul'skaya and ments to show that chlorine gas in the Vdovenko (I4E) used the spectroair stream during combustion increases the volatility of germanium. graph to determine germanium, berylLIERCURY. Aidin'yan (1E) deterlium, and scandium in coal ash. Valeska mined mercury in coal by calciniiig the and Havlova (ZSE) spectrographically coal in a glass tube with PbOl. determined titanium and manganese in coal without ashing, by a spark on A mixture of 0.25 gram of coal and a medium-dispersion spectrograph. 0.50 gram of PbO, is placed in the glass Keclewska (P4E) used a polarobulb, to which a small wad of calcined graphic method to determine trace asbestos and another 0.25 gram of PbOs are added. The bulb is heated gently amounts of heavy metals in coal ash. 5 to 7 min. until the water is exThe values for copper, lead, zinc, and pelled, then it is heated in a more cadmium obtained b y this method intense flame. The mercury distills and agreed completely with those obtained condenses on the cold wall of the spectrographically and spectrophototube. Evaporation takes 8 to 10 metrically. minutes. The bulb is removed, and 1 ARSENIC. Ault (4B) reported the ml. of 1% iodine in lOy0 K I is added development of a method to determine to the tube and allowed to stand 4 to 5 arsenic in coal. The organic matter is min.; 4 ml. of HzO are added, and the destroyed by heating the coal in a solution is transferred to a container for colorimetry. The mercury in the solumixture of RIgO and KMnOa in a tion is determined by comparing the stream of oxygen. At this point two color of CuHg13 produced by adding methods are possible, a colorimetric CuS04 to standards of known mercury molybdenum blue procedure, as decontent. scribed by Crook and Wald ( Q E )or , the PHOSPHORUS. Gibson and Ode (1OE) Gutzeit method described by Ault and compared volumetric, colorimetric, and Whitehouse (6E). 80 R
ANALYTICAL CHEMISTRY
gravimetric methods for phosphorus in coal and concluded the three methods are interchangeable without sacrifice of accuracy. Bhattacharyya, Bhaduri, and Banerjee (YE)used a complexometric titration to determine the phosphorus in coal. The phosphorus was extracted from the coal ash with HC104 and precipitated as magnesium ammonium phosphate. The magnesium in the precipitate was determined by titration m-ith EDT.4. The method is simple and rapid, and the maximum mean deviation is generally less than O.OOl5%;. Heilpern (IRE) proposed the use of a strong reducing agent, 1-amino-2-naphthol-4-sulfonic acid, t o produce a sharply differentiated molybdenum blue without heating in the determination of phosphorus in coal and coke ashes. Roy and Gupta (I7E) used a mixture of H2SO4, " 0 3 , and HC1 to evtract the phosphorus from coal ash. After dilution it is boiled, filtered, and precipitated from the filtrate as ammonium molybdophosphate, dissolved in standard alkali, and back-titrated with nitric acid. The method does not require platinum mare. Roy and Gupta ( 1 8 3 ) eliminated the interference of silica in the determination of phosphorus in coal ash by eytracting the phosphorus from the ash with 2.27 HSO3, followed by precipitation as the ammonium molybdophosphate. S ~ D I I JAND V POTASSIUM. The following method for the determination of sodium and potassium in coal ash m s proposed by Schuhknecht and Schinkel (21E). Powdered ash (100.0 mg.) j, weighed into a platinum crucible, moistened with HZO, treated n i t h 10 nil. of HF and 0.5 ml. of H2S04, and evaporated t o fumes, 2 ml. of concentrated HC1 are added and the solution is reduced to 0.5 ml. by warming. The contents of the crucible are transferred to a 250-ml. volumetric flask. A 25-ml. aliquot is mixed with 5 ml. of a buffer solution 250 grams of (50 grains of CsCl 1000 grams of A41(s03)39H20 HzO), and the mixture diluted to 50 ml. and burned in a CzH2-airflame. Maximum deviation for KzO is 0.057, and for SazOis 0.027,.
+
+
OTHER & E x w T s . Rhenium was determined in coal by Kuznetsova (16E). She heated 20 grains of coal with a mixture of CaO (40 grams) and K l I n 0 4 (1 gram) in a porcelain crucible a t a maximum temperature of 600" C. After 6 to 8 hours a t this temperature, the residue was extracted n-ith water containing bromine and filtered, and the precipitate was washed with water. The filtrate ITas evaporated to 10 ml. and filtered into a separatory funnel, and 3 nil. of freshly prepared 10% solution of potassium butyl xanthate and 10 ml. of concentrated HC1 n-ere added. The red molybdenum-xanthate
complex was extracted with 5 to 10 ml. of CHC13, and the molybdenum-free solution was transferred t o a 50-ml. colorimetric cylinder; 10 ml. of X a F solution (5yc) n-as added to avoid interference of vanadium. After a few minutes the following were added in order: 3 ml. of XHYSCS (20%), 2 nil. of PbCL solution (35% in HC1). and 5 nil. of isbpentyl aleohorsaturated with the misture of reagents. The J ellow color is compared rTith standards containing knon n amounts of rhenium. Vranium in coal ash n a s determined by Schonfeld ~t al. (1OE). The coal ash iq evaporated several times with HF and then with HXOs to give a solution 8% in HSOs. The uranium is then eytracted n ith ethyl acetate and transferred to a fluoride pellet for fluorescence measurements. Yttrium n as determined spectrographically in coal ash by Xrnautov and Shipiloi- ( S E ) , They mixed the coal ash sample with carbon in the ratio of I :1, placed it in cavity of the carbon electrode, excited it n i t h a x . arc discharge a t 9 amperes, and photographed on a medium spectrograph. Spectra are conipared with standards of knoim amounts of Y2O3. Laboratory Coking Tests. P ~ a s TICITT TESTS. Kedron and Muller (61.’) surveyed the various methods suitable for laboratory testing of coals for coking characteristics. The following methods nere declared suitable: Sapozhnikor plastometer, dilatometers, Roga caking indes. Jushnirevich method osity, Gieseler plastometer, and a method of following t h e coking process in a laboratory furnace. h modified form of the penetration plastometer was developed b y Callcott and Innes ( I F ) and the results of its operation were examined. -4new teehnique R as proposed for determining the fusion and resolidification temperatures. The thermal properties of the retort determine the distribution of the temperatures in the coking charge. Coking and plastometer tests on se1 era1 blends of high-volatile coking coals suggest that some coke properties are determined in part by plastometric properties. Soth (IOF), using the Gieseler plastometer in a study of the effect of oxidation of Sunnyside coal, ‘uspects that many inconsistent results of Gieseler plasticities may be due to changes in the coal. Llodifications of the Gieseler plastometer by Waters (If F) improved its performance and reproducibility of the results. The modifications include: means for minimizing frictional losses, adopting a uniform loading procedure, and automatically controlling the rate of heating Lange, Radmacher, and S’ierneisel ( ? F ) made an exhaustive examination of the dilatometer in the evaluation of coking coals. Inert coal or mineral
matter decreases both the expansion and contraction of highly coking coals, and if in not too great amounts, increases the coke strength. The dilatometer test aids materially in determining the cokability of coal mixtures and has great value in selecting the proper coals for blending of the coking charge. The Gray-King carbonization assay vras modified b y Das Gupta et al. ( 2 F ) by replacing the specially processed standard quality electrode carbon with crushed coke dust of graded size. CARRONIZBTIOPI’. Eckhardt and Xashan ( S F ) modified the Bauer carbonization test apparatus to carbonize 20 grams of coking coal in a quartz tube. The tube was heated in a special furnace with controlled temperatures in each of four zones. By moving the tube through the heaters, the coal charge passed from zone 1 to zone 4 in 25 minutes. Tar was separated at 110’ C., and the gas, after removal of ?;Ha, HsO, COS, H2S, and crude light oils, was passed into the holder. Results for samples of coals and blends indicated that the carbon content of the product gases could be estimated from results of coals used in blends. The equipment was also used to study the effect of oxidation on coking coals. With increase of oxidation the carbon content of the products of carbonization was reduced, the volume of gas increased, the CO increased, and the hydrogen and CH4 decreased. The coking behavior of coal n-as investiqited using a crucible heated in an oren and supported by a microbalance, and with a “churn-type” plastometer. The rate of weight loss n-as correlated with the softening characteristics and degree of oxidation. Nikolaev ~1 al. ( 8 F ) have shown that the coking behalior of coking coals in commercial operations can be closely estimated by coking a 2-kg. sample of coal in a n electrically heated laboratory oven. Kesler ( 6 F ) used the international code classification to evaluate blends of coal to be coked. The properties of mixtures are related to the mechanical strength of the coke. The fluidized carbonization of coking coals n-as carrirtl out by Iida et al. (@’) in a 12b-mm.-dianieter retort. Inner and outer systems of heating to 700” to 800” C. produced a 50% yield of semicoke ponder. Sand, iron sand, and coke breeze are some of the inert materials used to prevent agglomeration of the coal. The fluidized-bed carbonization of brown coal was studied by Riedel ( 9 F ) on bench-scale and pilot-plant equipment. Basic questions of aerodynamics of the equipment, residence time, and reaction time nere clarified. By using 0 to 8 mm. of coal, throughputs as high as 2020 kg. per sq. meter per hour were obtained.
Standard Methods. SATIOKAL STANDARDS. T h e compilation of standards on coal and coke, published b y t h e American Society for Testing a n d lllaterials ( d S T l I ) , contains specifications, definitions, methods of sampling, methods of chemical analysis, physical testing, and classification of coal by rank (fG). The 1959 edition is in the process of revision and will include the new and revised methods developed in the interim. Yew tentative standards approved relate to fusibility of ash (D 1857-61T), preparing coal samples for analysis (D 2013-62T), expansion or contraction of coal by the sole-heated oven (D 2014-62T), and calorific value of solid fuels by the adiabatic bomh calorimeter (D 201562T). Tentative standards advanced to standard status relate to Standard Definitions of Terms Relating to Coal and Coke (D 121-621, Yethod of Test for Carbon DioAide in Coal (D 1756-60), Method of Test for Sulfur in Coal Ash (D lTd7-60), and Method of Test for Equilibrium lloisture in Coal (D 141256). Shipley (SG) reviewed the revised methods of the British Standards Institution. He refers to the changes made in individual tests to improve accuracy and reduce the time required for analysis. Radmacher (?GI compared the German methods with the reconimendations or proposals of the IS0 Technical Committee 27 on Solid Mineral Fuels. The report includes methods for proximate and ultimate analvsis, dilatation, caking, ash fu4on characteristics, heat of combustion, coke strength, and other proposed specifications. IXTERNATIOSSL SrAXD ~ R D S . The British Standards Institution holds the secretariatship of Technical Committee 27 on Solid Mineral Fuels of the International Organization for Standardization ( E O ) . IS0 has continued to press forward in the development and standardization of international standards for the sampling, analysis, and testing of coal and coke. Only one of the 21 items on the agenda for study is in abeyance. The others are all under study or have adIanced to an IS0 recommendation, n hich is the most advanced state of any IS0 standard. Table I gives the status of work through December 1961. 1Iore recent working groups have met on the direct determination of oxygen, coke testing, and sampling. Miscellaneous. A method for determining the porosity of coal was developed b y Ettinger and Zhupakhina ( J H ) . The true densities of the coals were determined in water with a wetting agent; the particle densities were determined by coating the surface with an impervious film produced b y VOL. 35, NO. 5, APRIL 1963
81 R
the hydrolysis of an organosilicon vapor. The results are in good agreement with determinations of helium density, and particle density b y geometric measurements on regular shapes. Porosities calculated for the determined -;slues are in fair agreement with those determined b y Moffat and Weale. Mazyczuk (6H) determined the true density of 121 coals in ethanol and apparent density in mercwy. These values were used to determine the correlation among density, ash, and spontaneous combustion. The absolute density of coke mas determined by Thibaut and Vigneron ( 8 H ) . They used a finely pulverized sample in water, benzene, and toluene, and reproducibility mas possible for any particle size smaller than 74 microns. Dutta, Rai, and Chakravorty ( 2 H ) ivere able to estimate the ash softening temperatures of ash from mixtures of coal within 50°, 97% of the time, from the composition of the ash. Other relationships were noted between the fusibility of ash and ash composition. The fusion temperature of coal ash tends to increase with a n increase of the SiOz content, as shown by the -41208 work of Kunstmann, Bodenstein, and Gass ( 5 H ) . Yao and Wang ( Q H ) devised two empirical formulas for calculating the fusion temperature of coal ash based on the composition of the ash.
Fuel gases include: blast-furnace top gas, carbureted water gas, coal gas, coke-oven gas, gas from underground coal gasification, industrial gas, liquefied petroleum gas, manufactured gas, natural gas, producer gas, synthesis gas, and water gas. The review by Hobbs (W) should be
Table 1.
Item No. 1
2
3
+
+
4
5
Y.WI = 24 A1203 11 (SiOn - TiOn) 7 (CaO MgO) 8 (Fez03 KNaO)
+
+
+
+
(1)
Y.TV2 = 200 -k 5 (Fe20s
+ 21 A1203 + 10 SiO, + CaO + MgO + KPl’aO)
6
(2)
Y.W1 and Y.W2 are fusion temperatures, and Y.W2 is the simplified form with the chemical symbols representing the percentages of the components. Hubacek and Krejcik ( 4 H ) revived the use of the molybdenum-resistance furnace for determination of the fusibility of coal ash. The British Standard manometric method for carbon dioxide in coal was modified by Burns ( 1 H ) to accommodate Australian bituminous coals. The apparatus was calibrated with a coal containing a known amount of carbonate carbon. Palowitch and Nasiatka ( 7 H ) by a centrifuge method reduced the time from 24 hours t o 1 hour for a float-andsink separation of 1410-micron or finer coal. GASEOUS FUELS
The term “fuel gas” may be applied to any gas that can be burned. The methods reported are those which have been applied specifically to fuel gases.
82 R
ANALYTICAL CHEMISTRY
7 8 9
10 11
12
Status of
consulted for fundamental developments in gas analysis. Zanen ( 4 4 reviewed and discussed in detail the sampling and analysis of gases. He has included four charts of correction factors for determining the Wobbe and Delbourg indexeq of fuel gases.
Work of I S 0 Technical Committee 27
Item Determination of moisture
Stage of Development (i) Revised draft proposal for total moisture being prepared for circulation as Draft IS0 Recommendation (ii) Revised Draft IS0 Recommendations for moisture in analysis sample by direct gravimetric method and direct volumetric method being prepared for submission to IS0 Council (iii) Revised draft proposal for moisture-holding capacity (general method) being prepared for circulation as Draft IS0 Recommendation Simple and rapid methods being investigated Determination of ash IS0 Recommendation 158 published Determination of calorific (i) Revised draft proposal for calorimetric value bomb method being prepared for circulation as Draft IS0 Recommendation (ii) Draft proposal for adiabatic honib method being studied Determination of carbon and (i) Revised Draft IS0 Recommendation for hydrogen Liebig method being prepared for submission to I S 0 Council (ii) Revised draft proposal for high temperature method being prepared for circulation as Draft IS0 Recommendation (i) IS0 Recommendation 159 for Strambi Determination of total sulfur method published (ii) Revised Draft IS0 Recommendations for high temperature method and Eschka method being prepared for submission to IS0 Council Determination of nitrogen Revised Draft I S 0 Recommendations for Kjeldahl method and semimicro Iijeldah1 method being prepared for suhmission to IS0 Council Draft proposals for direct method being Determination of oxygen studied Determination of volatile Revised draft proposal being prepared for circulation as Draft 1SO Recommendamatter tion Suggestions being studied Reporting of results Revised draft proposal being prepared for Determination of ash fusicjrculation as Draft IS0 Recommendability tion Swelling and caking tests (i) Revised draft proposal for crucible snelling number being prepared for circulation as Draft IS0 Recommendation (ii) Revised Draft IS0 Recommendation for Audibert-Arnu test being prepared for submission to IS0 Council (iii) Revised draft proposal for Gray-King test being prepared for circulation as Draft IS0 Recommendation (iv) Limit of agglutinating value: in abeyance ( v ) Revised Draft IS0 Recommendation for Roga method being prepared for submission to IS0 Council (vi) Other methods being studied Determination of phosphorus, (i) Revised draft proposal for phosphorus in ash being prepared for circulation as chlorine, and arsenic Draft IS0 Recommendation (ii) Direct method for phosphorus deferred for consideration later
(Contznued)
Atrakovich ( I J ) reported on laboratory apparatus and routine methods for the determination of HzS and other sulfur compounds, nitrogen oxides, and cyanides in coke-oven gases and natural gas. Compressibility factors and equilibrium water-vapor contents in grams per cubic meter n-ere determined at
Table I.
Item NO.
Status of Work of I S 0 Technical Committee 27 (Confinued)
It mi
14
Determination of forms of sulfur Methods of sampling
15
Mineral matter
16
Coal preparation
17
Brown coals and lignites
18
Physical testing of coke
13
Chemical analysis of coke
19
20 21
three temperatures (O", 25", and 50' C.) and pressures to 350 atm. An increase of equilibrium water-vapor content was observed in the presence of higher paraffins and COz. Tin4 ( S J ) has reviewed the snmpling and analysis of gases. His book, which was w i t t e n for application to combus-
Sampling of coke Classification of solid mineral fuels by size and type Physical properties of coal Determination of carbon dioxide
Stage of Development (iii) Revised Draft IS0 Recommendations for chlorine by bomb-combustion method and the high temperature method being prepared for submission to IS0 Council (iv) Revised draft proposal on chlorine by Eschka method being prepared for circulation as Draft I S 0 Recommendation ( v ) Revised draft proposal for arsenic by absorptiometric method being prepared for circulation as Draft I S 0 Recommendation I S 0 Recommendation 157 published (i) Revised draft proposal on sampling of hard coal being prepared (ii) Draft proposal on glossary of coal sampling terms being prepared for postal ballot Revised draft proposal being prepared for circulation as Draft I S 0 Recommendation (i) Revised draft proposal for coal preparation terminology being prepared for postal ballot (ii) Revised draft proposal on symbols for coal preparation plant being prepared for circulation as Draft IS0 Recommendation (iii) Draft proposal on flow sheets for coal preparation plant being prepared for postal ballot (iv) Draft proposal for expression and presentation of results of coal cleaning tests being prepared for postal ballot ( v ) Methods for calculation of yields of products being studied (vi) Methods for float-and-sink analyses being studied (i) Revised draft proposal on yield of tar, water, gas, and coke by low temperature distillation being studied (ii) Draft proposals on determination of moisture, ash, and benzene-soluble products being prepared for postal ballot (iii) Other methods being studied (i) Revised draft proposals on hIicum and Shatter tests being prepared for circulation as Draft I S 0 Recommendations (ii) Revised draft proposals on size analysis and bulk deneity in small container being prepared for circulation as Draft I S 0 Recommendations (iii) Revised draft proposals on total moisture, moisture in analysig sample, and ash being prepared for circulation as Draft I S 0 Recommendations (iv) Other methods being studied ( v ) Draft proposal being prepared In abeyance (i) Grindability by Hardgrove method being
studied (ii) Size analysis being studied Revised draft proposal for pressometric method being prepared for postal ballot
tion phenomena of interest iii aeronautics, is an excellent general survey of the subject. The section on sampling includes a discussion of flow problems, location of sampling probes, and probe shapes and mechanical design. Sampling. Gouff4 a n d Gaudry ( I K ) have described an apparatus which collects a representative sample of gas being metered by a rotat:onal meter. -4small aliquot is obtained for each revolution of the meter and discharged into a gas holder a t atmospheric pressure. The total sample taken is proportional to the absolute pressure of the gas stream, because the small aliquot volume a hich discharges to 1 atm. is alternately filled to full line pressure and to a regulated 2-atm. absolute. The apparatus has been used between 2 and 20 atm. absolute A portable apparatus ( 2 K ) has been developed for producing a niivture of fuel gas and air for analysis. Fuel gas and air are measured and mixed in cylinders provided with adjustable pistons. Suspended Matter. ;\loore, Ehrenfeld, and Wiederhorn (9L) have described instruments for collecting and identifying particles in a gas stream. They clacsify instruments in til-o principal categories: monitoring inQtruments and particle collection devices. The monitoring instrument that has been employed to the greatest extent in particle work is the forn ard-angle light-scattering instrument. This device measures the intensitv of the light scattered bv the suspended particles. Other monitoring instruments of interest are the electrostatic surface area meter, the charged-11-ire impinger. and jettape collectors. The collection devices remove samples of the particles suspended in the gas stream in a form such that they can be examined either with the microscope or by usual chemical and phrsical techniques. Such instrumentation includes filters, impactors, thermal precipitators, impingers, and centrifugal separators. Among the developments in microscopic techniques haye been the use of the electron microscope and phase contact microscopy. Automatic scanning of a particle collection field is also a major development. .4 complete analysis of the particulates in a gas stream should provide information on the size distribution of the particles and their chemical coniposition as well as a measure of particle concentration. Microchemical techniques ha\ e been developed for the determination of the chemical composition of suspended matter. Izmailov ( I L ) reported the continuous measurement of the dustiness of gases based on the measurement of the value of an electrical change induced in the particulate matter under a defined set of conditions. This instrument, d i i c h is
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APRIL 1963
83 R
recommended for blast-furnace gases, determines the degree of dustiness by measuring the current amplitudes. The apparatus consists of a tube, fabricated from a n insulating material, one end of which contains two coaxial electrodes on which the corona is produced by alternating current. A current collecting electrode is situated a t a certain distance from the corona. A simplified formula for the current is Z = IC 1 s uj p , in which k = a proportionality constant, 1 = tube length of the collecting electrode, s = seconds, w = the electrical field (frequency of the corona in radians per second), and p = the maximum volume density of the collecting electrode in coulombs per cubic centimeter. Chemical Methods of Analysis. I n modern analytical chemistry most methods depend to some evtent on instruments to make the final measurement of t h e constituent of interest. T h u s the methods described here may be titrimetric, colorinietric. volumetric or barometric, gravimetric, and electrometric. The electrometric methods may be further defined as conductometric, ainperometric. coulometric, and potentiometric. A modern Orsat apparatus was described in detail by Rracht (4.11) with a surrey of analytical procedures for COS, 0. CO, H, CH,, and ethylene. A critical comparison is made with other methods of analysis, particularly gas chromatography. Orsat analysis is satisfactory for determining the utility of coke-oven gas and for coke-oven plant control, but gas chromatography is better suited for accurate analyses and for determining the higher hydrocarbon constituents. Gas chromatography is also recommended Imrticularly for the determination of nitrogen. Ebersbach and Ruch (7-11) discussed the application of the Orsat apparatus to the analysis of flue gases. The relative merits of I arious absorbents for COz, 0, and CO are discussed. Frequently encountered sources of error and the manipulation of the apparatus are described in detail. Barcndrecht and Janssen ( scribed the use of four-electrode conductometry for the automatic determination of COz and ammonia in concentrated scrubbing water of coke-oven gas. This technique is especially useful where solutioiis are contaminated with oil and tar. Two electrodes carry a 50- or 60-cycle a x . through the solution to be analyzed, and the potential difference produced is measured with the other two electrodes. The use of a cell of special construction renders the measurement remarkably independent of the flow rate of scrubbing water through the cell. HYDROCARBOXS. Drabkin (5M) reported that naphthalene determinations as carried out by the standard picrate
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ANALYTICAL CHEMISTRY
method are subject to error from naphthalene homologs, which also form picrates, and from absorption of indene by the naphthalene picrate. They are also dependent on reaction conditions, such as temperature and concentration of the picric acid solution, and gas flow rate. The standard method is suitable only for the analysis of purified gas. The picric acid method was improved by keeping the picric acid solution near 0" C., separating the picrate, washing it, and then dissolving it in CHC13 and titrating one portion with alkali. Lebedeva and Markachea (14.1f)also reported that high values are obtained by the picrate method because of the formation of picrates of compounds other than naphthalene. They conducted a qualitative test of coking-gas components that crystallize on cooling to 0" C. IvBnyi and R6na (1131) investigated the determination of naphthalene in municipal gases with picric acid. They stated that in a heterogeneou. system where the naphthalene is carried by a gas stream, the most ini1)ortant factor is the temperature of the absorption tower containing the picric acid solution. They recommend 4" to 6" C. as the ideal temperature. Pozdeeva (1731) performed the polarographic determination of naphthalene in coke-oven gas. He first purified the gas in a series of wash bottles or tubes containing, in the following order, 80% H~SOI, 337, S a O H , anhydrous CaC12, and two Drechsel bottles containing the solvent for the naphthalene. The electrolyzer, in addition to the mercury anode, contained 0.037 gram of Bu4XI, 0.75 cc. of dioxane, and 0.25 cc. of HsO. Parallel determinations by the polarographic and picrate methods of gas samples from four different plants were in poor agreement because unsaturated compounds, along with other components that react with picric acid, had not been removed from the gas. Kubant and Stepnickova (1331) emphasized the necessity for the remoL-al of olefins before attempting a polarographic determination of aromatic hydrocarbons in coke-oven gas. The aromatic hydrocarbons are separated by cooling to -75" C. and are nitrated in the same vessel by using 10% ",SO, in concentrated H?S04. The waves of the dinitro compounds are then recorded in alkaline media. Drabkin and Rabin (6-11)found that the amount of gasoline produced by the oil shale industry exceeds the amount predicted from gas analyses involving adsorption on activated carbon. An investigation showed that adsorption on activated carbon giles results that are too low for the gasoline content of the raw gas, but satisfactory results for purified gas. Upon cooling the gas
stepwise to -70" C., the gasoline was condensed completely and the results were in accordance with production values. HYDROGEECYANIDE. Gunther (10-If) described a method for HCN. Results agree very well with those obtained by the standard RrCN method but the method is characterized by lower requirements in apparatus and procedure. His method, however, can be used only for town gas which is free from H2S, according to the Deutschen T'ereins T. on Gas- und Wasserfachmiinnern standard. and for other H2Sfree gases. SULFURCOUPOCEDS.Goksoeyr and Ross (931) developed a method for the determination (in
