THE UNIVERSITY OF ILLINOIS LIBRARY YM5

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2 THE UNIVERSITY OF ILLINOIS LIBRARY YM5

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5 BURNING LIMITS AND TOUGHNESS OF SHALE FROM THE GALESBURG DISTRICT BY IDRIS NELSON THESIS FOR THE DEGREE OF BACHELOR OF SCIENCE IN CERAMICS COLLEGE OF LIBERAL ARTS AND SCIENCES UNIVERSITY OF ILLINOIS 95

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7 UNIVERSITY OF ILLINOIS June 55 THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY _ Idrls Nelson ENTITLED BURNING.LIMITS AND TOUGHNESS OP SHALE FROM THE SALESBURG DISTRICT IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE degree of BacmLor of Scenc e. n Ceramcs APPROVED: head of DEPARTMENT of Ceramcs

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9 UNIVERSITY OF ILLINOIS 90 THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY ENTITLED IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF- Instructor n Charge Approved: HEAD OF DEPARTMENT OF

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11 A * INTRODUCTION Purdy^* says "It s essental that a shale have certan physcal and chemcal propertes n order that t may be used for the manufacture of pavng brck. Of the physcal propertes the more mportant are plastcty tensle strength bondng power and fneness of gran*" The frst three are necessary n order that the shale may stand the treatment receved n the manufacturng process. Nevertheless these propertes vary greatly n degree n the dfferent shales used for pavng brck purposes. Extreme fneness of gran s not desrable snce fne graned clays have not proved to be good pavng brck materal. Snce there s lttle data due to the lack of knowledge of the mneralogcal consttuton of clay only one of the chemcal propertes the amount of fluxng materal n the shale seems to have any defnte effect upon the propertes of the manufactured product. The above propertes refer to the shale n the raw condton only. After burnng certan other propertes are essental n order that the shale may be sutable for pavng brck. Brck should possess (a) toughness (b) hardness (c) strength (d) homogenety of structure (e) freedom from lamnaton (f) weather-resstng qualtes (g) regularty n form and sze and (h) unformty n qualty. Toughness n pavng brck s understood as that property of resstance to sudden stresses as from mpact wthout rupture. It may be consdered as the opposte of brttleness. Hardness s the ablty to resst abrason such as the grndng acton of steel tred wheels movng over a pavement. Strength s mportant because the load s concentrated on a small area. The brck are frequently subjected to large transverse stresses. Purdy. Bu. 9* - Illnos Geologcal Survey.

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13 - 2 - Homogenety of structure and freedom from lamnaton are desrable because they assure a greater unformty of wear upon the pavement and also ndcate greater toughness and strength. Otherwse the brck chp and spall badly under heavy traffc. Weather- resstng qualtes:- porous brck wear away rapdly under the freezng thawng and wet weather condtons. Regularty n form and shape unless the brck have ths qualty t s mpossble to lay them properly Unformty n qualty n a gven lot of pavers assures a pavement whch ra.ll wear evenly over the whole surface. In addton to these requrements of the burned product the shale must have certan burnng propertes. The necessty of hardness and toughness n the brck requres burnng to vtrfcaton understood as the pont at whch the brck mmersed n water wll not absorb more than 3% of ts dry weght. Snce a consderable range n temperature s found n large commercal klns even under the best condtons of burnng t s desrable that the shale develop about the same degree of vtrfcaton wthn the wde temperature lmts. Thus unformty of the product s assured. Vtrfcaton s due to the closng up of pore space n the burned product when t approaches the fuson stage. Each of the dfferent mneral consttuents of a clay has a dfferent fuson temperature and t s the softenng of these varous consttuents when ther respectve fuson temperatures are approached that determnes the range of vtrfcaton for any partcular clay. Expermental data has proven that ths closng up of pore space takes place through dfferent temperature ranges for dfferent clays also that t depends upon the duraton of the burn. Thus we fnd clays whch have a long range of vtrfcaton gve no partcular dffculty n burnng but the clays whch have a shorter range

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15 - 3 - of whch Illnos shales are a good example cause consderable trouble. In ether case a temperature beyond the maxmum pont of the vtrfcaton range causes the pore space to ncrease agan gvng an overburned product. Ths s known as "bleb" structure and s detrmental to the strength and toughness of the brck. To avod the development of ths "overburned" condton n all parts of the kln t s advantageous to ncrease the duraton of the burn and lower the fnshng +h«temperature. The same degree of vtrfcaton can be thus obtaned as wth a hgher temperature n a shorter perod of frng and wth less danger of bleb formaton. There s also danger of overburnng even at lower temperatures. Brown and Murray^ concluded that "Vescular structure s produced by a contnued burnng at a low temperature as well as by excessve temperature" also as a rule "the hgher the content of fluxes the more marked wll be the nfluence of the tme factor." The vtrfcaton range s determned by means of a porosty-temperature carve the decrease n porosty beng plotted aganst the ncrease n temperature. Thus clay havng a long range of vtrfcaton has a gradually slopng porostytemperature curve whle clay havng a shorter range shows an abrupt drop n porosty. A techncal examnaton of the entre depost can be made by determnng the porosty-temperature relaton of samples from the varous parts of the bed so that the varatons of the depost may be carefully studed and the dffcultes whch such varaton mght cause avoded n manufacture. In nearly every shale depost there s more or less varaton n the workng propertes n dfferent portons of the bed due to mpurtes such as thn layers of sandstone or other foregn materals and to greater weatherng acton n some parts than n others. Wth ths fact n mnd the wrter endeavored Brown and Murray.- Functon of Tme n the Vtrfcaton of Clays. Translatons: Amercan Ceramc Socety. Vol. 5 p. 93.

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17 - 4 - to establsh some relaton between the property of two shales taken from the same depost and used for pavng brck purposes e The two shales were obtaned from the Galesburg dstrct and wll hereafter n ths paper be desgnated as Shale A and Shale B. Shale A s of a blue varety and belongs to the coal measure seres lyng between the horzons of "coals 3 and 4." It s a depost about ffty feet n thckness wth thn partngs of soft sandstone. Shale B s a contnuaton of ths depost but of a yellow nature and perhaps slghtly coarser. Ths color s due no doubt to the fact that some of the ferrous ron compounds have been changed to the ferrc state by oxdaton and that some of the organc matter has been removed by the weatherng processes chat have acted upon ths part of the depost wth greater rapdty than upon the remander. The followng lmts of composton of Shale A have been taken from over a hundred analyses made n the laboratory of the plant. S to 68.0 % 7.00 to 3.60$ 6.20 to 8.2$ CaO.54 to.49$ MgO.62 to.67f. Na 2 0 K to 6.73$ Loss on Ignton 3.58 to 5.2$

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19 - 5 - From several analyses of yellow Shale B the followng lmts were obtaned. S to 72. A 2 3 Fe to 0.67/. 7.9 to 8.45/ CaO.56 to.65?* MgO.68 to.47js Na 2 0 K to 6.43$ Loss on Ignton 3«56 to 4.46$ From the comparson of the chemcal analyses t s found that the only notceable dfferences that occur seem to be n the SO2 A 2 3 and volatle matter. Shale B shows a hgher percentage of S0 2 and a lower percentage of AI2O3 and volatle matter. The loss of volatle matter can be accounted for by weatherng acton and the hgher 50 2 content s probably due to the fact that S0 2 was left when the thn sandstone layers were weathered. Shale A s more dense and fner graned than Shale B. The dsks of A average about 3«5$ more n weght after beng burned than those made of Shale B although the dryng and burnng shrnkage s the same. The approxmate specfc gravty of Shale A s 2.66 and of Shale B s As to ther workng propertes there s no notceable dfference between them. Both have moderate plastcty and form a compact body of excellent qualty n the course of manufacture. The present study s dscussed under the followng headngs: (l) Character grndng moldng dryng and burnng of test peces. (2) Absorpton test. (3) Descrpton of Rattler test. (4) Conclusons.

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21 - 6 - Preparaton of Test Peces The two samples of clay were gven as nearly as possble the same treatment n all the expermental work. Both were ground n the dry pan and passed through an eght mesh screen. They were then tempered n a wet pan to a stff mud consstency passed through a small expermental auger brck machne havng a round de three and one-half nches n dameter. A baffle plate was placed just back of the de to decrease de lamnon as much as possble. The clay was cut nto dsks approxmately two and one-half nches thck. These were carefully dred n a steam dryer for about thrty-sx hours. Several of the dsks made of Shale B splt apart on dryng due to the fact that the clay dd not weld completely after passng the baffle plate. Both clays possess excellent dryng qualtes and nether showed any dryng defects other than noted above. The dsks of both clays were placed n a round down draft ol fred kln and burned together. The duraton of the burnng was approxmately thrtysx hours exclusve of the water smokng and oxdaton perods. The temperature was rased approxmately 35 per hour durng the entre burn. A pyrometer was used to regulate the rate of heatng and cones to determne the degree of heat treatment. The heat dstrbuton n the kln was kept as unform as possble. Tral peces were drawn from tme to tme and broken to determne the condton of hardness. It was noted that Shale B was less vscous than Shale A at the fnshng temperature because some of the dsks were kln marked. The kln was closed when Cone was slghtly bent a.-d allowed to cool n approxmately fortyeght hours. Absorpton Test After beng taken from the kln each dsk was weghed and mmersed n water for forty-eght hours after whxch t was agan weghed and the percentage absorpton calculated. The dsks were then thoroughly dred and sorted nto

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23 - 7 - groups accordng to the percentage absorpton. Rattler Test vs. Absorpton Relatve toughness of the dsks showng varyng percentages of absorpton was determned by an abrason test n a small expermental rattler. The rattler was a cylndrcal ron mll thrty nches n dameter and ffteen nches n wdth outsde measurements. It was rotated at a rate of 45 R. P. M. for thrty mnutes n these tests. The charge conssted of twelve dsks and three hundred pounds of wrought ron balls one and seven- eghths nches n dameter. Prevous expermental work wth ths rattler on other clays gave results whch compared favorably wth a standard rattler test made on the same clay under commercal condtons.

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25 - 8 - Test Dsks Percentage No. Nos. Absorpton f Weght* Average Clay A n grams f Percentage before after Loss loss Rattlng:. I * t * < _ L " t III * * H » <.66 * « \ 0» \» 9.23 « J «78.22» U * * \ I \ 5330 «460 \ ( ( :» \

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27 Clay A Test " Dsks Percentage v Weght n grams Percentage No. Nos. Absorpton Average before» after Loss loss Rattlng r- j 4 -V A $ 6 A $ $ 7 A IV ] * * 5260 \ j : : V ] j \ ~* r- j- VT V J.45 * ] * » J 22.0

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29 woo Test HO* DISKS.r ere ercage ADsorpxon I 4U I pu CA «AA AQ AA 40 AQ < Average Clay A wexgrx xn u runs j ue ore sxer l l j VII : fto o2. /Q a.88 T AA 40 l jo oa J Aft 7n (U J - < > l - j Loss < Percentage loss 070 \ 20.24» I j 99 AA. oo A<7.07? 9o ~r - r " I TTTT VIII ] I T A : ( : "I /I O 00 : AQ AQ Aft era H j- IX s AA 00 7 Aq 09 Arr op AA I.682 j 5305 : 420.» < 095 ] ? u >

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31 - - Test No. Dsks Nos. Clay A Percentage Weght n Grams Percentage j Absorpton Average before j after Loss loss L Rattlng J_ : j X I ll 20 : j : : :.90 * j j j..88 H XI :.90 : r\r\ :.89 : : : : j 8.0 XII : 39.0 :.0 : ] w.39 : 79 j 05 J :.09

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33 Nos Clay A Test No. Dsks I Percentage Absorpton T Weght n Grams Percentage Average before after Loss loss Rat^ln^ J I XIII I : l 2.34 XIV ll l XV I * * : * I I

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35 - 3 - Clay A Test No. Dsks Nos. Percentage Absorpton Average 7/eght before \ n Grams after Loss j Percentage loss I Rattlnf t t 9 of XVI 42 \ > t : ^ I f f : : : II l : \

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37 Perc Test No. Dsks Nob Percentage. Absorpton Average Weght n Grams before after Rattlng Loss entage loss l j III 59 * l [ y* [ j [ I 20 IV j H VI

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43 - 5 - Conclusons From the results obtaned Shale B was found to be more susceptble to kln markngs than Shale A whch ndcates that t has a greater change n vscosty for small temperature ncreases. From smlar data Brown^ concludes that ths ndcates a shorter vtrfcaton range. On examnaton the dsk appeared to be glassy ndcatng that the maxmum safe burnng temperature had been reached for Shale B. Although the tests do not all bear out the statement t s probably safe to say that there s a defnte relaton between the percentage absorpton and the rattler loss. The hgher the absorpton the hgher wll be the rattler loss. Ths s especally marked after % absorpton was passed for Shale A and b% for Shale B. A smlar concluson was drawn by Brown^ n testng clays for pavng brck purposes. G. K. Brown. -A Method of Testng Clays for Pavng Brck Purposes. Trans. Amer. Cer. Soc. Vol. 6 p. 57* G. H. Brown. -The Vscosty of Some Shales at Furnace Temperatures. Trans. Amer. Cer. Soc. Vol. 2 p. 265

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45 Dsk A and B before rattlng

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48 /XX Or.

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