CONTINUOUS TUNNEL KILNS AT THE PLANT OF MOUNT CLEMENS POTTERY COMPANY1,2

These two direct-fired kilns (bisque and glost) are placed end to end in a specially constructed kiln building 825 feet long. Both kilns are fired with soft coal, hand stoked. Three motors are required, aggregating 8/14 horsepower on each kiln. Hydraulic car pushers are employed. A pressure of 8100 lbs. is required to move the 44 cars thru the bisque kiln. The bisque kiln cars hold 278 dozen ware each and at a 55-minute car schedule, deliver over 7200 dozen ware per 24 hours at a fuel saving of more than 85% over the former periodic kiln operating at this plant. This bisque capacity is equivalent to that of thirteen 16/12 ft. diameter periodic kilns which would cost more to build than the bisque tunnel kiln.     

THE RESISTANCE OF SINGLE CLAY BODIES TO THE ACTION OF STEAM1

Twelve whiteware bodies were made, consisting of 51.41%, clay, 10.69% North Carolina feldspar, and 37.9% flint, one clay being used in each body. Twelve clays were studied. The specimens made from these bodies were fired in the regular tunnel bisque kiln to cone 9, glazed on one side, and fired to cone 4 in the glost kiln. The trial pieces were then subjected to the autoclave test, with the steam at a pressure of 100 pounds per square inch, maintained for a period of 3 hours. Of three American ball clays none was found to have caused crazing. In the case of four domestic kaolin bodies, one crazed in part, two were noncrazing, and one shivered. Of five imported kaolins, one of the bodies was noncrazing. While lower absorptions bring about a craze-resisting condition, it was shown that of two single clay bodies with practically the same absorption, one may resist the steam action and one may not. The structure of the clay is an important factor in this connection.     

RAPID FIRING OF SEMIPORCELAIN*

Some of the factors limiting the firing cycle of semiporcelain ware are listed. Satisfactory seven-inch bisque, eight high, was obtained with a complete firing cycle of 15½ hours. Satisfactory glost was obtained with a complete firing cycle of 8½ hours.     

NOTES ON THE OPERATION OF DIRECT FIRE TUNNEL KILNS1

The successful application of the direct fire car tunnel type kiln in firing of semivitreous chinaware is described. The bisque kiln firing to cone 9 one-half down is 332 feet 11 inches long, the placing height at middle of crown being 6 feet and the placing width 5 feet 1 inch. The glost kiln operating at cone 5 has the same placing height and width as the bisque but the length is 301 feet 1 inch long. The ware is placed in saggers as formerly. Natural gas is used as fuel and is supplied to kiln through Maxon Premix burners; an auxiliary fuel oil system can be used in case the gas is not available. After a year's operation some of the important concliisions drawn are as follows:

• 1 The heat distribution is not ideal.
• 2 There is no appreciable difference in labor cost a t this plant than in the older ones.
• 3 There is a considerable saving in fuel.
• 4 The sagger loss is much less than in the older type plants.
• 5 The direct fire tunnel kiln has proven siiccessful from the commercial standpoint in manufacturing semi-vitreous china.

     

WASTE HEAT DRIERS FOR WHITEWARE

This drier is so constructed that the flow of air is transverse to the tunnel. A fan produces a change of air four to six times per minute, drying ten tons of filter-pressed clay in twenty-four hours. The drier may obtain its heat either from the kilns, glass or bisque or steam coils, or the use of both.     

CORRELATION OF GLAZE-BODY STRESSES WITH THERMAL PROPERTIES OF WHITEWARE BODIES*

Several lead borosilicate glazes with high to low thermal expansion were applied to a bisque whiteware body having porosities ranging from 20 to 30%, and the thermal properties were studied. Test pieces were subjected to an autoclave test at 50, 150, and 300 lb. per sq. in. and to a thermal-shock test by quenching from 400° to 600°F. into cold water. The thermal-expansion curves for the various glazes and for the body at each porosity were determined on the interferometer. The glaze-fit ring test was used to determine the degree of tensile and compressive stress, and these stresses were plotted graphically with the body porosity. The resistance to crazing was increased in both the autoclave and thermal-shock tests as the thermal expansion of the glazes, as measured on the interferometer, decreased. The 10% porosity body gave the best results in the thermal-shock test. A close correlation was found between the thermal-expansion curves for the glazes and bodies of varying porosity and the stress characteristics shown by the glaze-fit ring test.     

EARTHENWARE BODIES AND GLAZES1

Effect of body composition on crazing .—-Six bodies of each of 2 standard clay compositions were prepared with variable clay and flint content and after biscuiting at cone 8 were glazed with 21 earthenware glazes and glost fired at cones 4 and 6. The results indicated that the variability of the silica content of clays would not be great enough to produce crazing in a well-balanced glaze. Effect of proportion and composition of frit .—-A standard whiteware glaze was compounded in 6 different ways and several other glazes in 2 ways. It was found that the method of compounding had no effect on crazing but it affected the gloss and fusibility. Increase in the percentage of material fritted increased the gloss and fusibility. With the same percentage of frit the best glost and highest fusibility were obtained when the flint and part of the clay were included in the frit. Effect of some variations in glaze composition .—-Substitution of CaO by Na₂O, pound for pound, as well as direct addition of Na₂O, increased crazing, improved gloss and increased the fusibility. Direct addition of feldspar increased crazing slightly and diminished gloss, but did not noticeably affect the fusibility. Substitution of 1½1/2 parts of feldspar for one part of flint to maintain the same fusibility increased crazing and diminished gloss. Direct addition of CaO improved gloss, increased fusibility and slightly reduced crazing.     

THE TEARING OF VITREOUS ENAMELS*

Similar to other enamel shop problems, tearing has not been reproducible under controlled conditions in the laboratory. Experiments show that tearing is caused by a cracking of the bisque before enamel fusion. To produce bisque cracking experimentally in the laboratory, a ground-coated cross-bend strip, 2 by 12 inches, was covered on one side with a coating of the test enamel. The enamel was dried, and before firing it was flexed to a predetermined degree in a Danielson-Lindemann cross-bending machine. The strip was fired, and the degree of tearing was studied. The effect of various factors, such as grinding fineness, application, clay, and other mill additions, in overcoming tearing difficulties was determined by this method. Certain materials which overcome tearing do not prevent bisque cracking but cause the cracked bisque to heal rather than break away during the firing process. Experimental results are given.     

耐火材料窑炉设计中的优化选材

根据耐火材料工业几种主要窑炉的使用条件 ,结合耐火材料的性能特征 ,概括总结了耐火材料工业几种主要窑炉优化选材的原则 ,并举例进行了说明。     

A STUDY OF THE ABSORPTION OF TWO EARTHENWARE BODIES AND THEIR RESISTANCE TO CRAZING IN THE STEAM TEST1

An ivory and a white earthenware body fired in different positions of periodic and tunnel kilns and maturing to various absorptions were subjected to autoclave steam treatments at the pressures of 100 and 150 lbs. per sq. inch. The ivory body resisted the crazing induced by this test for absorptions from 7 to 8% in the 100-1b. pressure treatment. The white body withstood the destructive effect up to an absorption of 8.5%. Within a narrow range, thorough glost firing had some effect in increasing the resistance. In the 150-1b. test, the critical resisting absorption was lowered to 6% for each body.     

A novel low-clay translucent whiteware based on anorthite

This study was carried out to characterize the properties of a novel low-clay translucent whiteware suitable for daily use. The low-clay whiteware is produced from coarsely and finely milled prefired materials of the same composition plus a small amount of clay. It consists of anorthite (CaO·Al₂O₃·2SiO₂) and mullite (3Al₂O₃·2SiO₂) crystalline phases and a glassy phase with high crystalline to glassy phase ratio. The development of needle shaped long mullite crystals that were forming three dimensional interlocking network had significant effect on the elimination of pyroplastic deformation during glaze firing. Typical flexural strength and fracture toughness values were ∼110 MPa and ∼1.85 MPam^1/2, respectively. The low-clay whiteware had relatively low (4.6 × 10⁻⁶/°C) thermal expansion coefficient which made possible to glaze the whiteware with a typical hard porcelain glaze. A continuous interface layer was produced between the whiteware and the glaze and no crack was present through layer because of expansion mismatch.     

铝酸锶蓄光型发光材料的研究

蓄光型发光材料是近年来应用比较广泛的一种发光材料。笔者选用铝酸锶铕镝体系，以高温固相法、共沉淀法、微波法、溶胶-凝胶法等制备发光材料，并通过控制不同原料的配比、pH值、温度等条件，探讨了上述因素变化与材料发光特性之间的关系。     

二次烧成高档瓷的研究

采用高温素烧、低温釉烧工艺，利用江西周边常用原料进行二次烧成高档瓷坯、釉料的研究，探讨了熔块釉与硅酸铝质瓷胎坯釉相适应性、铅溶出含量问题。     

铝酸钙蓄光型发光釉料的研究

研究了各种(稀土)掺杂铝酸钙的蓄光型发光釉料及其制备方法，以高温固相法、共沉淀法、微波法、溶胶-凝胶法等制备发光材料，并通过控制不同原料的配比、pH值、温度等条件，探讨了上述因素变化与材料发光特性之间的关系。     

废弃物综合利用与生态环境材料

本文从生态环境材料的角度讨论废弃物综合利用中存在的问题及其研究进展。研究表明,利用废弃物煅烧过程中会有部分重金属逸放,在没有专门处理废气Hg污染的设备下,Hg含量较高的城市污泥不宜直接用于煅烧陶粒或砖,否则会造成二次污染。Hg、Pb含量较高的废弃物用作煅烧水泥熟料时,回转窑窑灰也不宜再次入窑,但可作为混合材生产水泥,从而减少Hg、Pb的逸放造成环境的污染。而立窑不宜使用Hg、Pb含量较高的废弃物煅烧水泥熟料,否则会产生二次污染。烟气脱硫灰渣用于水泥生产需注意SO2污染及对水泥性能影响的问题,可利用脱硫灰渣生产高性能水泥调凝剂和高性能砌筑水泥或砂浆。     

NOTES ON MOISTURE EXPANSION*

Moisture-expansion determinations were made over a period of more than three years on bisque and glazed specimens of two types of semivitreous bodies having approximately the same absorption which were exposed to four different atmospheric conditions. The data indicate the cone 0 tale-pyrophyllite body to expand less under all conditions of exposure than the cone 9 clay-flint-feldspar body. Glazed specimens of both bodies expanded more than the bisque specimens and a possible explanation is given. From mathematical considerations, a three-year storage period appears to be sufficient to permit moisture expansion that closely approaches the ultimate which might be expected in the types of bodies investigated. The autoclave treatment gave the highest expansion values and should serve as an index of the service performance as to delayed crazing of ware so tested.     

水泥窑铅镉等重金属的污染及防治

利用原子吸收分光光度法、振荡溶出等方法,研究了水泥窑铅镉等重金属污染的防治.氟会促进Pb,Cd,Zn和Cu的逸放.无论何种水泥窑,Hg逸放率高达89%～96%.Pb,Cd,Zn和Cu在不同类型水泥窑中其逸放率有明显差别,立窑的逸放率较高,Pb和Cd为84%～90%,Zn和Cu为36%～47%;湿法回转窑次之;新型干法窑的逸放率最低.使用高效的除尘设备,不仅可减少粉尘的污染,还可减少Pb等重金属的逸放.把Pb等重金属含量较高的窑灰用作水泥混合材既可使Pb等重金属被固封于水泥混凝土中不会产生二次污染,又能减少因窑灰循环入窑而导致Pb等重金属的再次逸放.     

水泥窑的SO_2污染与防治

研究了几种类型水泥窑ＳＯ２污染的状况,硫在原燃料中的存在形式对其逸放的影响,并对目前水泥窑ＳＯ２污染的防治问题进行讨论。