T H E J O U R N A L OF I N D U S T R I A L AND ENGIATEERING C H E M I S T R Y .
550
dioxide as 0.56 per cent. b y volume, but state t h a t several times during the month the concentration rose slightly above the 0 . 7 5 per cent. prescribed as maximum b y the Court. The outcome of the hearing was the entering of a judgment b y agreement and stipulation between the contesting parties whereby the plant is allowed thirtyfive days under existing conditions in which t o run through the ore on hand, b u t is then required t o close down completely until such time as i t can live up t o the letter of the original decree, viz., remove all solids, never exceed 0 . 7 5 per cent. sulphur dioxide and do no damage. During the time in which the plant still remains in operation experimentation and development is being carried on as vigorously as ever, but it is scarcely expected even under the most favorable conditions t h a t a shut-down can be entirely avoided. During such shut-down, however, the progress of the work a t other plants already undertaken thoroughly insures the uninterrupted development of the process in general.
PAPER- MAKERS’ CLAYS. By J. STEWART R E M I N G T O N ,
DOUGLAS
A . BOWACKA N D P E R C Y DAVIDSON.
Received April 17,1911.
The commerical value of a china clay for use as a loading material depends largely upon the whiteness of the body, and essentially its freedom from grit and sand. For example, should “fillers” be used which contain more gritty matter than is desirable in a china clay, the detrimental effects on the machinery will be quickly noticed, more especially when the wear and tear of the wires is taken into consideration. T A B L E AND
RESULTSO F
Aug., 191I
latter, especially the compounds containing iron, exercise a great influence on the color of the natural clay, and it is therefore imperative t h a t the fullest use should be made of information gathered from a chemical analysis. The iron exists chiefly in the form of ferric oxide (hydrated), ferrous carbonate (siderite), ferric sulphide (pyrites) and occasionally as ferric silicates. Hence, although the actual figures found for iron on the analysis of any two samples may correspond, it is known t h a t deposits vary so much in their physical and chemical properties t h a t the percentage of iron is not a direct criterion of the value of a china clay for paper-making purposes. It is not, therefore, sufficient t h a t merely the amount of each constituent of clay be ascertained: information is required as to the various proportions of true kaolin, silt, sand and gritty particles present, and also the state of fineness of the sample. The foregoing is best obtained by mechanical analysis, the principle of which consists in carefully and systematically washing the clay in an apparatus specially devised for the purpose, whereby the lighter “true-clay’’ substance is readily washed away from the larger and heavier constituents. Moreover, if desirable, the residual matter may be microscopically examined in order t o ascertain the exact nature of the different minerals in the clay. To obtain evidence as t o the nature of the various clay deposits in England i t is necessary t o compare the composition, color and fineness of the best known brands, and with this object in view the following summaries have been prepared from a selection of analyses and reports, made b y the authors t o the interests of paper manufacturers concerned:
THE PRACTICAL INVESTIGATIONS
- ...
Analyses: Chemical Constituents
c;
UY
6’:
mal
:E
O L
No. of Silica. Alumina. clay. 1 2 3 4 5 6
,
8 9 10
11 12 13 14 15 16
17 18 19 20
SiO2. 46.21 46.32 47.60 47.74 45.74 46.46 48.16 46.20 46.60 46.28 46.38 47.26 46.12 46.90 46.86 46.62 49.92 44.82 %.74
46.76
A1203. 39.82 39.76 38.26 37.66 36.84 37.40 38.45 36.23 37.48 38.38 39.00 37.84 38.80 38.53 39.24 38.98 38.43 38.69 37.87 38.06
Ferric oxide. Lime. Magnesia Total Alkalies. MgO. water. KzO. Fe208. CaO. 0.45 0.10 12.81 0.38 0.23 0.41 0.11 0.40 0.31 12.69 12.40 0.42 0.20 0.55 0.57 0.61 0.22 0.58 0.59 12.60 0.60 0.11 1.86 11.06 3.79 2.00 11.81 0.86 0.21 1.26 2.06 0.50 0.14 10.59 0.10 1.57 0.76 0.11 11.00 4.13 0.64 0.22 1.26 12.74 1.06 1.03 12.87 0.66 0.72 0.15 0.79 12.70 0.44 0.58 0.11 12.07 1 .os 0.54 0.29 0.82 0.82 0.15 1 .os 12.62 0.41 12.49 0.76 0.11 1.01 0.20 12.24 0.61 0.15 0.75 0.15 0.81 12.30 0.50 0.69 0.10 0.71 1.18 0.21 12.77 0.78 1.30 0.94 0.20 12.79 1.26 0 89 0.50 0.24 12.44 1.36 0.86 0.82 0.20 12.01 1.29
The coloration of the clay, which is of the greatest importance, is due partly t o organic matter and partly %o the various minerals contained in the clay. The
no .u
QI.
Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00
100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 E 100.00
100.00 100.OOjD 100.00 100.OO)c
$Z
BO A
E
D B
I:c C
D D B A B B
A
0.09 0.07 0.32 2.96 0.24 2.22 3.90 4.10 1.19 1.30 2.35 1.15 0.61 0.77 0.98 2.28 2.10 0.93 1.12
100 100 95 75 85 70 65 65 90 90 90 75 90 90 90 90 75 75 90 90
Suitable uses for: Coating papers Coating papers High-grade papers News High-grade papers and coating papers News Cheaper loadings and news Cheaper loadings and news High-grade papers High-grade papers High-grade papers News High-grade papers High-grade papers and coating papers High-grade papers and coating papers High-grade papers Ordinary white printings Ordinary white printings High-grade papers High-grade papers
The results of the investigation of this representative list of clays point t o the conclusion t h a t these products are of first-rate commercial value, and com-
Aug., 1911
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y .
pared with corresponding figures furnished b y some other good specimens of clays previously examined, the opinion formed is that many of them could hardly be surpassed in purity and quality. An important and interesting fact will be a t once noted regarding the relative values of these deposits; viz., with a few exceptions the specimens are remarkably uniform in character and on the whole may be considered as representing a high standard of perfection now reached in the progress of a great industry. On comparing the figures of the clays marked No. 6 t o No. 8, with those yielded by the samples obtained from other deposits, it is evident that there is a great difference in the proportion of iron contained in these minerals. A corresponding difference appears in the general character of the clays, notably when compared with those marked Nos. I t o 4, and those marked Nos. g to 1 2 , which are finer and possess a much better color. The latter variation may be partly owing to a difference in the nature and extent of the surrounding beds, or to some local circumstances affecting the cleaning of the material and the nature of the clay produced. The presence of a comparatively high percentage of alkalies in the clays Nos. 5 and 8 points to the fact that the clay is associated with an unusually large quantity of unaltered feldspar and some micas, while the potash content found on analysis indicates the presence of “muscovite,” one of the characteristic minerals of the crystalline rocks, granites, etc. This information leads one to suppose that the clay has been mined near some point of gradation of the true kaolin and the primary bed: a corresponding increase of the constituents of the original rock is noticed, which serves to confirm this impression. With regard to the question of the properties imparted t o papers by the use of different kinds of fillers, one can hardly differentiate between values of the best qualities: a t least, when dealing with highclass grades, such as the above mentioned. One might go further, however, and say that more attention should be given by consumers t o the question of the state of fineness of the clays acquired for the purpose of loading. For example, clays are not uncommonly found on the market which to all intents and purposes are equal in purity and color t o the wellknown brands of standard clays, but, on a physical examination, they are proved t o contain as much as 8 t o 1 2 per cent. of grit, and sometimes even 18 per cent. Again, the question of difference in price is often very little, the rate being but slightly lower than that demanded for really high-grade material. I t will be readily understood from this digression that the absolute analytical figures, unless interpreted b y a skilled chemist, do not accurately gauge the entire value of the clay, because the component parts of the foreign dkbris, usually associated with clay, bears a close relationship to the ratio of the constituent elements in the true kaolin itself. It behooves buyers, therefore, to attach due importance to the classification which is based on the composition fur-
551
nished under this system of mechanical separation of the gritty particles. AYNSOME
TECHNICA LA LB O R A T O R I E S ,
.
L A N C A S H I RENGLAHD. E.
_----A SCHEME FOR THE RAPID ANALYSIS OF CEMENT. B y CLARENCE N. WILEYAND \I7.A. ERNST.
Received June 15, 1911.
Chemists who are engaged in the manufacture or testing of Portland cement have long wished that they could obtain a complete analysis of a cement, the composition of which was in question, without proceeding with the tedious and lengthy method generally employed. This method, in order to be accurate, calls for the solution of the cement in HC1, evaporation t o dryness, followed by a short baking in order t o render the silicic acid entirely dehydrated and insoluble. This evaporation must be carried out with more or less care, because if the evaporation is made a t too great a temperature or in too hasty a manner, and extreme care is not taken, the gelatinous silicic acid, in being freed from its water, will spatter and danger of loss is incurred. The operation requires a t best from three to four hours, and if all of the silicic acid is not dehydrated, a loss is bound t o occur through silica passing through the filter. The old method for the separation of iron and alumina, by means of fusion with potassium acid sulphate, is also a source of annoyance to the busy chemist. Fusion must be carefully watched until the liquid stage has been reached, and even then, if the heat is not carefully adjusted, frothing or boiling over is frequent. To make this fusion requires time and attention taken from other, perhaps more important, work. The solution of the cake is again an occasion of delay and the reduction of the iron present, to be properly accomplished, requires several hours and, if the iron is in large quantity, even longer. The determination for magnesia also consumes much time and i t is the general custom t o allow the granular crystalline precipitate of magnesium ammonium phosphate to completely subside so that filtration may be speedily accomplished. A complete analysis of cement, therefore, covers a period of two days’ time, although it can be done in the course of one day by careful manipulation. The authors have been searching for some time to find a method whereby accurate results could be obtained in a much shorter time. They had already adopted the schemes for the determination of magnesia and the separation of iron and alumina, which will be described later, but had found no suitable method for the rapid accurate determination of silica. Some, time ago there appeared in Tonindustrie Zeitung, 35, 2 6 5 , a method described by C. Hentschel, whereby silica can be accurately separated from cement by means of acetic acid and in a very short time. Here, a t last, appeared the solution of our problem, and upon the first trial of this method we knew that the operation of cement analysis could be accomplished in a few hours’ time. The method described by Hentschel is as follows:
