SEPTEMBER, 1935
INDUSTRIAL AND ENGINEERING CHEMISTRY
1099
distinguish more or less quantitatively between films which to other rapid tests are indistinguishable, and holds out some promise therefore of making possible a more logical search for a material, or for the conscious preparation of a film, which
a film, as is the case in all the practically important instances of general corrosion.
will happen after the lnetai surface has become covered with
RECEIVED April
Literature Cited
9, 1935
Rare Elements in German Brown-Coal Ashes
WALTER FUCHb
\ew
Jersey igricultural Experiment Station, New Brunswick, S . J.
D
C R I S G an investigation on the production of activated carbon froin German brown cnal of the Rhine didrict, it wafound that some constituents of the ash exerted a catalytic influence on the velocity of combustion. T h e n the mineral constituent,5 were removed by treatment n-ith hydrochloric acid, a fair control of the acti\-ation procev became possible. In connection with another investigation concerning the possible use of brown coal as a fertilizer (S),a ccrtain favorable effect on plant growth could be traced back to the waterholuble substances in the coal, possibly the rare element's. Since the power plants in the brou-n-coal district near Cologne are producing as a waste material many tons of brown-coal ash daily, it seemed desirable to make detailed investigation of that ash. The ash taken for examination originated from ~
~~~
TABLEI.
~ ~ ~ _ _ _ _ _ _ _ _ _ _ _ _ ~ ~
~~~
~
ELEMZESTS F~CSD IN GERMASBROI+-S-COAL ASHES
Gravimetric Analysis Per cent Ca 35 56 Fe 10.74 >I g 4.86 Si 3.31 A1 1.60 Na 2.30 Ii 0.19 0 35 lln Traces P C , 0, H, N, 9 Also present
Spectrophotograyhic -1nalysis 10-6 p e r cent
Zn Ti Au Ga Ge
1. Lead, silver, mercury, bismuth, cadmium, coppel', platinum, osmium, iridium, tin, molybdenum, gold, tungsten. 2. Nickel, cobalt, manganese, zinc, iron, aluminum, chromium, titanium, vanadium, tantalum, columhium, thallium, zirconium. 3. Barium, strontium, calcium, magnesium, sodium. potassium, lithium. 4. Phosphorus, silicon, cerium, lanthanum, gallium ( 7 ) germanium (4);rhenium ( 6 ) . 5. Carbon, oxygen, hydrogen, nitrogen, sulfur. ~
Twenty-five of these element's were found in t'he coal, as shown in Table I. The amounts of the elements established by spectrographic analysis have been estimated in decadic intervals; in each case consideration was given to the intensity and, if possible, to the number of lines. These mineral constituents of brown coal may be of a primary or a secondary origin. It is possible to distinguish here several possibilities. The plants whose decomposition provided the material for the formation of brown coal, probably did not take up the mineral constituents in the same ratio as they were found in the soil, but rather acted as collectors. During the decomposition process, substances of an acid nature originated; the humic acids representing the bulk of the organic substance of the brown coal< are oxy-
10- 100 lo- 100 1- 10
Traces Traces
brown coal of the Grube Fortuna near Cologne. The neceasary .pectrophotographic analyses were carried out by the author's assistant, J. Clermont (9). The ash was brought into solution by treatment with aqua regia and also by fusion. The analyses were made by the rnethodi of Gerlach and Scliweitzer (5) and Schleicher and Clerinont (9). Utilizing the experiences of the latter, the wlutions were subjected t o electrolysis under varying conditions; when the p H was varied, different electrolytic precipitates were obtained, and these as well as the other precipitates obtained in the work were finally examined by a spectrograph ( 8 ) . A sample of a-h was also analyzed in the usual way (1). The examination wac extended to include thr. following forty-five elements :
TABLE 11. AhfOUSTS OF EIGHTEEN ELEMESTS IN COAL ASH, THE EIRTH'SCILUST, .4ND VARIOUS FORMS OF OROLNIC LIFE
Ca Fe
E: Si h1 h-a
Ii P
Coal .ish
Earth s Crust
%
%
Organisms
%
35.6 10.7 4.8
0.36 3.31 1.6 2.3 0.2
Trace
25.7 7.5 2.6 2.4 0.1
10-1- 1 1
ISDUSTRIAL .4ND ENGISEERING CHEMISTRY
1100
carbonic acids and are capable of salt formation as well as of base exchange ( 2 ) . In Table I1 the amounts of the ash Constituent. of the German brown coals are compared with the average concentrations of the corresponding elements in both the earth’s crust and the various forms of organic life as estimated by Vernadsky (10). I n case an ash constituent exceeds that of the organisms, a storing effect is obtained; if the amount of an element in the ash is midway between the values for the earth’s crust and for the organisms, a simple averaging ha, taken place; if an ash constituent represents the lowest of the three values, a loss during coal formation is probable. Calcium, iron, magnesium, and manganese are capable of forming insoluble humates, and the accumulation of these four elements in the ash may be traced back to this fact. The concentration of the elements silicium, aluminum, and sodium is apparently equalized. Potassium and phosphorus, both of the utmost importance in agriculture, seem to be lost by leaching. Some of the elements present in traces may have played a role in building up the extremely abundant forests of the brown coal period, and they may still play an
VOL. 27, NO. 9
important role in industrial processes; these two possibilities are open to further experimental work and consideration.
Literature Cited (1) Classen, d.,H a n d b u c h der analytischen Chemie, Vol. I, S t u t t gart, Ferdinand E n k e , 1922.
(2) Fuchs, W.,“ D i e Chemie der Kohle,” Berlin, Julius Springer, 1931.
( 3 ) Fuchs, IT., Gagarin, R., a n d K o t h n y , H., Biochern. Z., 259,85 (19331,
(4) Geilmann, W., a n d Briinger, K., 2. a n o r g . allocm. C‘hetn., 196, 312 (1931). (5) Gerlach, IT., and Schweitzer, E., “Die chemische Emissionsspektralanalyse,” Leipzig, Theodor Steinkopff, 1930. (6) Heyne, G . , a n d Moers, K., 2. anorg. allgena. Cheni., 196,143 (1931). (7) Papish, J., a n d Holt, D. A, J. Phys. Chem., 32, 142 (1928). (8) Schleicher, A., 2. Elektrochem., 39,2(1933). (9) Schleicher, A., a n d Clerrnont, J., 2. anal. Chem., 86,191 (1931). (IO) Ternadsky, W., “Geochemie,” Leipzig, Akademische Verlagsgesellschaft, 1930.
RECEIVEDApril 8, 1935. Presented before the Division of Gas and Fuel Chemistry a t the 89th hleeting of the American Chemical Society, New Y’ork, N. Y., April 22 t o 26, 1935.
Rare Elements in Coal Ashes V. M. GOLDSCHMIDT Mineralogical Institute, University of Gottingen, Germany
C
OAL ashes contain many elements in small amounts
which are not commonly reported in ash analyses t u t which may affect the behavior of coal in use. The high percentage of boron as borates or borosilicates in the ashes of many coals may influence the softening temperature and clinkering characteristics of the ash and so affect the combuction of the coal. Certain catalytically active metals, such a s vanadium, nickel, cobalt, molybdenum, tin, acd/or g e r r a nium which may be present in the mineral matter of coal, may be of importance in determining the nature of the products of distillation or hydrogenation of such coals. The high percentage of arsenic in a number of ashes, which may be concentrated in the flue dust and soot, may be an important source of pollution near industrial centers. The obEerved concentrations of certain elements in the ashes of coal tars, especially zinc, germanium, arsenic, silver, and cadmium. may be of importance in the subsequent industrial utilization of the tar or the products prepared from it. Carbon rods for spectral analysis prepared from coal may be rendered unsatisfactory by the presence of many elements in detectable amounts; only after much work was done by Bauer and Harmann on this problem was success achieved in eliminating even the last spectroscopical traces of these impurities. I n only a few cases studied in the past may the percentage of rare elements found in the ashes of coals be sufficient to warrant industrial recovery; one such case is the abundance of germanium in some coals. Rare metals and metalloids, which occur in the earth’s crust in amount less than 0.05 per cent, have been observed in the ashes of coal in many cases. Nearly 50 years ago Jensch (4) published data on the percentages of zinc, cadmium, and lead in coals from Upper Silesia. Forty years ago Jorissen (6) found in flue dust, derived from the burning of Belgian coal, the elements copper, zinc, tin, molybdenum, and lead. The occurrence of vanadium, sometimes in large amounts, in ashes of bitumen and other hydrocarbons
is well known. Sickel in amounts up to one per cent has been observed in ashes from British coals ( 7 ) .
IS THE course of an investigation on the percentages Q and distribution of the different elements in minerals, rocks, and ores the author observed that germanium, an (1)
element previously considered to be very rare, iq concentrated in considerable amounts in the ashes of many coals, even up to more than one per cent of germanium dioxide. Systematic investigation revealed that many rare elements are sometimes concentrated in the mineral matter of coal. The analyses have been carried out partly by chemical means and in most cases by the methods of quantitative optical or x-ray spectral analyses ( 3 ) This laboratory has developed the technic of quantitative chemical analysis by means of optical spectra; the majority of chemical elements have been observed to date (see, for instance, citation 6 ) . Concentration of rare elements, as compared with the average percentage in the rocks of the earth’s crust, has been observed in the ashes of many coals but not in all coals. Vsually the enrichment of rare elements in their mineral matter is the more marked, the less the total amount of mineral matter in the coal. It is remarkable that the rare elements which are found concentrated in the ashes of coals may have very different chemical properties; for instance, we find beryllium, strontium, barium; boron; scandium, yttrium, lanthanum, and the lanthanides (elements of atomic numbers 57-71) ; zirconium; vanadium, cobalt, nickel, molybdenum, uranium; copper, zinc, gallium, germanium, arsenic, antimony, cadmium, tin, iodine, lead, bismuth; silver, gold, rhodium, palladium, platinum (not yet tested or incomplete data, among others, thorium, indium, thallium, selenium, tellurium). In many cases all these elements, or most of them, have been concentrated in the same ashes. Besides the rare elements, some common elements may
