DELIQUORING BY EXPRESSION -PART 1 CONSTANT-PRESSURE EXPRESSION

The basic analitical method for so-called expression operation, the separation of liquid from solid-liquid systems by compression, are presented in view of the flow through compressible porous media. It has become evident that the expression mechanism consists of two flow phenomena. These types of phenomena can be analyzed by consideration of the flow mechanism through compressible porous beds, first by the filtration theory and second by the so-called consolidation theory. A simplified equation is also presented. It is shown that the simplified equation is well applicable to industrial expression problems even when the creep effects of matarials to be expressed are appreciable     

DELIQUORING BY EXPRESSION - PART 2 VARIABLE-PRESSURE EXPRESSION

Expression processes under variable-pressure condition are analyzed in view of the flow through compressible porous media. It has been demonstrated that the expression mechanism of slurry consists of two flow phenomena and these types of phenomena can be analyzed first by filtration theory and second by the so-called consolidation theory.

By assuming that the continuous screw expression process con- sists of a succession of batch processes, the basic equations ex- pressing the relationship between the dehydration rate, the feed rate, and the expression pressure distribution are derived.     

A CONSTANT-PRESSURE GRAVITY TANK FOR SPRAYING SLIPS AND GLAZES1

The difficulties in obtaining even coatings with gravity feed and the uniform results obtained with a tank equipped with a Mariotte tube are described. The construction and use of the device are explained and illustrated.     

INCREASING LIQUID EXPRESSION BY APPLYING LOW FREQUENCY VIBRATION

The use of low frequency vibration in combination with compression has been studied in the laboratory as a technique for improving the dewatering of compressible filter cakes. Experiments have been done with a variety of solids-water cakes over a wide range of squeeze pressures. Two types of apparatus were used: double membrane filter presses operating at 0.7 to 2.8 MN/m2 and a vacuum filter operating at 0.07 MN/m2. Frequencies of vibration were in the range of 0.5 to 60 cycles/min with the filter presses, and 30 to 120 cycles/min with the vacuum filter. Amplitudes of vibration were in the range of 4% to 10% of the unsupported filter cake span in both types of apparatus. Substantial improvements in compression dewatering were obtained in all the tests, and the power required to vibrate the filter cakes was low at just over 1 kWh/t dry solids. The thermal saving, equivalent to the additional water removal caused by vibration, ranged from 130 to 400 kWh/t dry solids.     

INCREASING LIQUID EXPRESSION BY APPLYING LOW FREQUENCY VIBRATION

The use of low frequency vibration in combination with compression has been studied in the laboratory as a technique for improving the dewatering of compressible filter cakes. Experiments have been done with a variety of solids-water cakes over a wide range of squeeze pressures. Two types of apparatus were used: double membrane filter presses operating at 0.7 to 2.8 MN/m2 and a vacuum filter operating at 0.07 MN/m2. Frequencies of vibration were in the range of 0.5 to 60 cycles/min with the filter presses, and 30 to 120 cycles/min with the vacuum filter. Amplitudes of vibration were in the range of 4% to 10% of the unsupported filter cake span in both types of apparatus. Substantial improvements in compression dewatering were obtained in all the tests, and the power required to vibrate the filter cakes was low at just over 1 kWh/t dry solids. The thermal saving, equivalent to the additional water removal caused by vibration, ranged from 130 to 400 kWh/t dry solids.     

陶瓷材料断裂源的声发射表征

研究了陶瓷材料在断裂过程中断裂源所激发的特征声发射信号，并将陶瓷材料断裂过程中所激发射与扫描电镜形貌观察结合起来，建立了断裂源，断裂形貌与特征声发射信号之间的对应关系，发现陶瓷材料的断裂源不同，其相应的特征声发射图谱也具有不同的特征，从而使声发成为陶恣材料结构缺陷评估的新方法。     

TANK BLOCK CORROSION BY SHELVING1

Photographs are given showing a number of glass tanks which indicate that part of the rapid eating of tank block is due to upward solution from cracks in the block wall. This upward solution is due to the higher specific gravity of the glass after dissolving tank block material. Experiments made by adding clay to glass melted in small pots and analyzing show this. The density is also taken of glass adjacent to the tank wall.     

VARIATIONS IN GLASS CAUSED BY HEAT TREATMENT1

The exothermic and endothermic effects detectable from the forms of the heating curves of a glass vary in magnitude depending on the previous heat treatment. With many of the common glasses, these variations bear a relatively simple relation to any changes in this treatment, but with others the relationship is not so easily established. Some glasses which are exceptional in this respect have a rather high silica content. It is shown in this paper that the previous heat treatment is always the chief determining factor in these variations. It should be possible therefore to obtain considerable information relative to the treatment a glass sample has received by simply studying such curves. It should also be possible to study in the same way, the relative effectiveness of the various heat treatments which may appear desirable. It is further shown that the density is affected by the heat treatment and in the discussion reasons are given for believing that many of the other properties of glass may be varied by the same means. In this connection some speculative views as to the nature of glass are included as aids toward explaining effects already observed and also for suggesting others which should be sought.     

THE PARTICLE ANALYSIS OF CLAYS BY SEDIMENTATION1

As a result of the analysis of Odén, it is possible to apply the sedimentation method quantitatively to the determination of particle distribution of clays in the dispersed state. An experimental procedure is described by which a number of points on the curve may be determined without the aid of any special apparatus. Sedimentation without the aid of a deflocculating agent gives valuable information as to the condition of the clay. Flocculated clays behave like jellies and the method of particle analysis cannot be applied in this case. Data concerning the usual physical properties are presented and these are found consistent with the results of the sedimentation tests as confirmed by microscope observations. The dispersed and fine grained clays are characterized by high dry strength, and the effect of deflocculating a clay is to increase its dry strength.     

相转移催化合成1-氯-2-邻甲氧基苯氧基乙烷

1 氯 2 邻甲氧基苯氧基乙烷是医药卡维地洛的中间体 ,它由愈创木酚和 1 ,2 二氯乙烷在PTC催化下 ,在碱中合成的。此反应条件温和 ,产率可达 70 % ,是合成 1 氯 2 邻甲氧基苯氧基乙烷的有效新方法。     

CORRECTION ON PAPER BY ROBERT B. SCHAAL1

The reasons for the corrective effect on copperheading of a modem double glass ground coat are explained. The boiling tendency of the steel sheets seems to be the primary Cause of copperheading, black specks, and a certain amount of fishscale. Pearlite has been found in the steel underneath copperheaded areas.     

IMPURITIES IN COMMERCIAL FELDSPARS OFTEN OVER-LOOKED BY ENAMELERS1

The author points out the necessity for careful selection and constant supervision of all raw materials, together with simple tests which the enameler may apply to such materials to insure a uniform product free from objectionable impurities.     

A STUDY OF PLASTICITY BY PRACTICAL POTTER'S METHODS1

By the use of the potter's wheel it is shown that bentonite added to non-plastic and lean ceramic materials will produce plasticity of the same quality as that found in high grade ball clays. Curves show the results obtained. The colloid theory of plasticity is sustained and it is demonstrated that mineral colloids of the type of the bentonites are of great value in ceramic work where plasticity is highly important.     

DIMENSIONAL CHANGES CAUSED IN GLASS BY HEATING CYCLES1

In obtaining expansivity curves for a medium flint glass, samples of the glass were tested which had previously received one or another of several different heat treatments, and in these tests heating cycles were employed which made it possible to determine that the magnitude of the so-called “permanent” changes in length are caused either by the annealing or the “disannealing” which may result from the heat treatment imposed on the glass by the heating cycle employed. Annealing decreases the length and specific volume, while disannealing increases them. It is shown that these effects are related to certain ice-point shifts observed in thermometers, and to other effects sometimes observed in various types of glassware.     

THE CORROSION OF TANK BLOCKS BY OPAL GLASSES1

The manufacture of opal glass in day tanks has made it necessary to study the corrosion of tank blocks. Opacifiers have to be used in larger quantities than in batches for opal glasses melted in covered pots because of the loss of density due to higher melting temperatures and shorter melting times, and exposure of batch to reactions from the direct flame heat. Experiments have been conducted to ascertain the factors which will allow the use of the lowest amount of opacifiers, the shortest practical melting time with the highest practical melting temperature, and also to minimize the corrosion of the bottom blocks of tanks by application of a cooling system, as well as prevention of separation of batch by practising certain “filling-in” methods of the batch, and as a final result to reduce block stones in the glass. The experiments have resulted in the successful operation of day tanks for opal glass and in prolonging the life of the tanks, and have made possible the manufacture of thin blown dense opal glasses of almost as good quality from tanks as can be produced in pots.     

CORRECTING TENDERNESS OF A SHALE BY CHEMICAL TREATMENT1

An attempt was made to increase the strength of a tender shale in both the green and dry states. Finer grinding, aging, and the addition of chemicals were the expedients used. Sulphuric acid increased the dry modulus of the shale up to 251% when used in concentrations up to 10%. This benefit was offset by a leaching of the color; 0.25% HCl and 0.25% tannic acid increased the dry modulus 42% and 72%, respectively. Organic binders as Bindex and glutrin showed a 100% increase. Two per cent Na₂CO₃ and 1% BaCO₂ showed a 60% and 45% increase. Molasses plus yeast improved the machining and the green strength of the shale. Finer grinding of the shale to pass 28- mesh and aging for one week improved the dry modulus 75.7%.     

THE STRENGTH OF GLASS AS AFFECTED BY CASING1

Considerable regarding the strengthening of glass by surface chilling has been written. Theoretically it has been shown that the modulus of rupture of slabs toughened glass may have a maximum of 3.4 times that of annealed glass. Complicated shapes and large surfaces cannot be satisfactorily treated by this method. Very similar results may be obtained by the method commonly called “casing,” wherein the article consists of three layers, the two outer ones being of glass having a lower coefficient of expansion than the inner layer. After annealing in the usual way the outer layers are left in compression and the central layer is in tension. By combining these initial stresses with those set up during a test to determine the modulus of rupture, a set of equations was derived. These equations were expressed in graph form, one of which gave the relation of case thickness expressed in tenths of the total thickness to the relative strength compared to flawless annealed glass. A number of curves were shown based upon the ratio of maximum internal tension to the maximum tension at the surface. These curves enabled the proper case thickness to be found in order to develop optimum strength for any assumed ratio of maximum internal tension to external tension. Another graph showed the corresponding initial tension and compression due to casing for the conditions outlined above. These curves showed that the case thickness could vary considerably without greatly affecting the strength and also that the initial stresses are smaller than those usually thought necessary. The maximum relative strength as developed by “casing” had a somewhat smaller value than that developed by “toughening.”