MXPA96005408A - Means of sand molding for dehie castings - Google Patents

Abstract

The present invention relates to a sand molding means comprising, in a dry base: silica sand ... 85% -95%, pre-mix ... 5% -15%, wherein the premix comprises : a clay component ... 70% -80%, a carbon component ... 15% -30% characterized in that the carbon component includes uintaite mixed with aqg

Description

MEDIA OF ARENA MOLDING FOR CAST IRON PIECES FIELD OF THE INVENTION The present invention relates to improvements in the cast iron and more particularly to improvements in the sand molding means used in the formation of molds in which molten iron is emptied in the production of castings.

BACKGROUND OF THE INVENTION Casting is an ancient technique in which a cavity is defined in a sand mold and then molten metal is poured into it. After the metal cools, the cast article is removed, with the sand mold that is usually broken in the removal process. The usual and basic procedure for the formation of such sand molds is to compact or squeeze a sand molding medium around a model and then remove the model, leaving a cavity having the configuration of the model. In order for the sand to maintain its configuration defining the molded cavity, it is necessary to provide a bonding agent that will cause the sand particles to adhere or join. Clay has long been an accepted and suitable liaison agent. The clay denotes a large group of anhydrous aluminum-silicate minerals. Individual mineral grains are considered microscopic in size. When it gets wet, clay is cohesive? plastic. When it is moistened and dried, the clay becomes permanently hard, particularly when it is dried at elevated temperatures.

DESCRIPTION OF THE INVENTION The present invention is specifically directed to iron casting, where the so-called casting in wet sand is a standard practice. This term means a process in which molten metal is emptied into a sand mold while it still retains the moisture that has been added to it for the cohesive properties of the clay to act. The sand molding means for iron casting comprise three basic components, mainly sand, clay and finely crushed anthracite, commonly known in the industry as "marine mineral coal". In use, a sand molding means is moistened with water to provide a medium that is capable of being compacted around a pattern to form a mold cavity. After the removal of the model, molten iron is emptied into the mold cavity while the sand molding means is still in its wetted or "wet" condition. The marine or marine bridging coal, on and immediately adjacent to the surface in the mold cavity, decomposes under the heat of the molten iron, as it is emptied into the mold. A product of this decomposition is elemental iron, in the form of graphite, in a shell between the mold cavity and the cast iron. This elementary graphite serves the primary function of allowing the solidified casting to be freed from the mold, free of sand particles. A secondary benefit of elemental graphite is that it extends to the level of the surface of the mold cavity, thereby producing a smoother surface on the cast article. In more recent times, it has been recognized that various advantages can be obtained by substituting alternate carbon sources for a portion of the marine mineral coal or the sea. In this way, there have been various proposals to use bitumenos or alfaltos, such as asphalt emulsions, small fragments - of asphaltene, petroleum fish and uintaite (an asphalt deposit that occurs naturally found in the Uinta Mountains in Uta and available by the American Gilsonite Co., Salt Lake City, Utah, under the Gilsonite trademark). The use of such alternate or secondary bitumenos or asphalts is discussed in an article, by the present inventors, published in the Journal of the American Foundrymans Society, Vol 95, pages 133-138 (Publication date 1978). At this point, it will be briefly noted that this is a well-established industry practice for a smelter to acquire a "pre-mix", which comprises a component of clay and marine mineral coal. The smelter then mixes the "premix" with sand from a local source to provide the sand molding means required for its operations. At least one premix that has a bitumen or asphalt sumplementario has been commercially available for several years. This is to refer to the use of an asphalt product (complex hydrocarbon) that is derived from the distillation of petroleum. This petroleum-based alfalfa is used in the form of an emulsion, that is, the asphalt is an over-cooled liquid in a highly dispersed emulsion. An advantage of this asphaltic emulsion is that it is richer in carbon than the anthracite mineral coal, that is, a smaller amount of the asphaltic emulsion is required for a given amount of the sand molding medium. It should be noted that the sand molding means using either single mineral coal, or mineral coal in combination with a supplementary coal source, ie, the asphaltic emulsion referenced, has suitable plasticity characteristics for the molding operations. . That is, it is striking that the cohesive plasticity of the sand molding medium is more critical in its "wet" condition, that is, when it is moistened. After being compacted to define a cavity, the "wet" molding means must have sufficient plasticity to resist any incident force for the removal of a model, so that the configuration of the cavity remains intact. Next, the sand molding means, when in a wet stage, must have sufficient plasticity to withstand the forces incident to the mold being moved and put back into various forms in the process when preparing it for the casting of metal into the cavity . In addition, the sand molding means must have sufficient cohesive plasticity to withstand the hydraulic forces incident to casting the molten iron within the cavity. Drying a "wet" mold occurs extremely fast and can occur while the metal is still molten and continues to exert hydraulic forces on the mold structure. Therefore, the dry plasticity of the molding means is critical in ensuring that the integrity of the mold will be maintained until the end of obtaining the molten articles of the appropriate configuration. It will be briefly mentioned that there exists another objective, significant characteristic of the means of molding sand, namely, permeability. Relatively high permeability is required in order to prevent damage to the mold when molten iron is emptied into the mold cavity. This is to point out that when the molten metal is emptied into the mold cavity, air must be displaced through the molding medium. More importantly, because the sand molding means is moistened, steam can be generated in a somewhat violent, or explosive, manner. Such steam must be vented through the molding medium with a minimum resistance to gas flow. All this requires a porous mold structure that has a relatively high gas permeability. The characteristics of plasticity and permeability are capable of objective determination and now the acceptable wet and dry plasticities are established for sand molding media, as well as permeabilities. After an article has been emptied, the sand mold is broken and then pulverized again for reuse. Over a period of time it becomes necessary to add fresh quantities of a clay and carbon additive. Similarly, it is a common practice to add fresh sand as well. This not only maintains a more or less constant ratio of the sand, clay and coal components, but also compensates for the accumulation of ash or slag that is a derivative of the decomposition of marine mineral carbon. The referenced premix, which includes an asphalt emulsion, has found acceptance due to various advantages. Primarily, these advantages lie in the ability to minimize costs by using less pre-mix and / or by reducing the total amount of carbon material in the premix. In addition, it was shown that the amount of pre-mixing of additional "complement", necessary in the recycling of a sand molding medium, was reduced. It was further demonstrated that this hybrid hydrocarbon pre-mix gave improved compactability, which facilitated the formation of molds, as well as minimizing the number of defective castings. These advantages were achieved, while at the same time the required minimum wet and dry plasticities were maintained. Also, the gas permeability characteristics were sufficient to properly ventilate the molds when the molten iron was emptied. Another factor to be observed is how the wet sand molding means was compacted around a model (in the normal case) to form a mold cavity. The characteristics of the sand molding medium can have a great impact on the "manageability" of the medium and the ability to compact, that is, to densify, the medium and also the ease with which the densification is achieved. This factor is relevant to the fact that both the wet plasticity and dry plasticity of a sand molding medium are directly provided to the density of the sand molding medium after it has been compacted to define the mold cavity. In this way there is a preference for the sand molding means having a handleability characteristic which facilitates obtaining a relatively high and consistent, desired density of the compacted molding means. While the "manageability" feature is subjective, it is nonetheless a recognized standard for sand molding media. Petroleum-based asphalt emulsions, referenced, have a limited number of commercial applications, or uses, beyond their use in sand molding media. Therefore, there is little encouragement for the widespread availability of this product. Therefore, there is an absence of price competition. For this and other reasons, such emulsions can be difficult to obtain in desired amounts and, in all cases, are relatively expensive. An additional disadvantage with this asphaltic emulsion is that the asphalt product derived from petroleum emits benzene, when it decomposes under the heat of the molten iron. While there has been no demonstrated danger of such benzene emissions, benzene is considered undesirable, if not harmful, in many situations. Recognize that government regulations are frequently imposed where there is no realistic danger, it is prudent and desirable to minimize to a great extent, if not eliminate benzene emissions from this aspect of the smelting operation.

The present invention focuses on prior blends employing marine mineral carbon and an alternate carbon source. In a more specific sense, the invention seeks to overcome the problems and drawbacks associated with the use of petroleum-based asphalt emulsions. A principal object of the invention is to provide a source of carbon-rich hydrocarbon carbon, supplementary to sand molding media used in iron smelting. Another object of the invention is to achieve the above purpose and, additionally, to minimize to a great extent, if not eliminate the benzene emission during the decomposition of the hydrocarbon in the emptying process. Yet another object of the invention is to achieve the above purposes in a manner that retains the necessary characteristics of a sand molding means for use in iron casting. A further object of the present invention is to achieve the above purposes and, additionally, further improve the ease with which the sand molding means can be densified and thereby provide increased plasticity for the sand molding medium in a further base. consistent.

For purposes of providing terms of reference herein, a sand molding means is defined as comprising silica sand and a premix. On a basis in weight, a sand molding means can comprise 85% -95% silica sand and 5% pre-mix. The usual and most preferred composition is 90% -93% silica sand and 7% -10% premix. The sand molding means of the present invention are proposed for use in the casting of iron and, for reasons discussed above, include a carbon component that decomposes to elemental iron, in the graphite form, when exposed to heat of cast iron in the process of emptying. In this way, the premix comprises a carbon component and a clay component. While the carbon component is comprised solely of marine mineral coal, the premix may comprise 70% -85% clay component and 15 Z-3% marine mineral carbon (the expensive component). Where a supplementary coal source is used, the coal component comprises marine mineral coal and a "coal additive". In the prior art, this "carbon additive" comprises a petroleum-derived asphalt, referenced, in the form of an asphalt emulsion. It will also be noted that the prior art teaches that the inclusion of a high molecular weight acrylic emulsifier (Reference Example 2) in a very small amount as a component of the "carbon additive" to increase the effectiveness of the asphalt emulsion. Where the carbon content of a sand molding medium is to be provided solely by parine ore or coal, marine or marine coal (coal component) and clay (clay component) are simply mixed together and combine to form a "pre-mix". Foundries acquire such "pre-mixes" and then add and mix them with locally acquired sand to prepare a sand molding medium. Where a source of supplementary coal is used, a "carbon additive" is prepared and added to the marine mineral coal, a "carbon component". Where an emulsifier is used, it is also added to the "carbon additive". The "carbon additive" can then be mixed with a marine mineral coal in the formation of the "carbon component".

It would also be possible for the "carbon component" or the "coal additive" to be marketed separately. The smelters could then acquire marine mineral coal and / or clay to form their own "pre-mixes". The purposes of the present invention can be achieved through the inclusion of water-miscible uintaite, preferably a petroleum-derived asphalt in the carbon component of the premix used in the formulation of a sand molding medium. In a broader sense, the invention is directed to a sand molding means comprising 85% -95% silica sand and 5% -15% premix. The premix includes a clay component and a carbon component. The clay component may comprise 70% -85% of the premix and the carbon component may comprise 5% to 30% of the premix. The carbon component can then comprise 25% -85% of marine mineral coal and 75% -15% of coal additive. The carbon additive may comprise from 25% -100 of uintaite mixable with water. While the uintaite has previously been used as a source of secondary or - or - supplementary carbon in the sand molding media, its use did not find acceptance to any substantial degree. The uintaite, as previously used, was not "mixed with water". While the uintaite not mixable with water, substantially reduces, or eliminates, the benzene problem of petroleum-derived asphalt does not offer the same advantages as petroleum-derived asphalt. That is, the non-mixable uintaite with water does not provide the same compaction and molding facility, does not provide similar wet / dry or permeability plasticities, does not reduce the amount of "complement" pre-mix or the "add-on" carbon additive. ", necessary for the recycling of sand molding media. Uintaite mixed with water is available from American Gilsonite Co., Salt Lake City, Utah, under the designation "Gilsonite miscible with water" (Gilsonite is the trademark of American Gílsonite Co.). Gilsonite mixable with water is simple uintaite that has been treated with a surfactant to provide a water-clear characteristic. However, the property mixable with water has been found to make uintaite a highly effective ingredient in improving the characteristics of sand molding media.

The sand molding means including uintaite mixable with water, likewise minimizes substantially, if not eliminating, the benzene emissions during the smelting process. Furthermore, the use of water-mixable uintaite provides substantially the same advantages as are found in the use of petroleum-derived asphalt, if not actually increasing such advantages. Additionally, it has been found that the dispersions of the water-miscible uitana can be, in general, substituted, on a basis in equal weight for the oil-based asphalt emulsions. Such direct substitutions do not necessarily provide the best results that can be obtained through the use of the water-miscible uintaite, but these, at least, substantially minimize, if they do not eliminate the benzene emissions. Where the water-mixable uintaite is included in the carbon component of the premix, it could comprise 100% of the "carbon component". The economy and other factors make advantageous a "coal component" comprised of marine mineral coal and a coal additive, with the mixed uintaite with water that is included, as a source of supplementary coal in the "coal additive" . The preferred composition of the "carbon component" is 74.% -86% of marine mineral coal and 1% to 26% of coal additive, with water-mixable uintaite solids that are 3% to 39% by weight of the carbon marine mineral. An additional advantage of the water-mixable uintaite is that it is compatible with clays that are conventionally used with, and have been found reliable in improving the plasticity necessary for the sand mold medium for iron. In this way, it is preferred that the "clay component" of the "premix" comprises approximately 50% of southern bentonite and 50% of western bentonite (see Example 1). In a more specific sense, the purposes of the invention are to achieve by means of a water-miscible emulsion of the uintaite, preferably including a small amount of an acrylic, high molecular weight emulsifier, as was done with the petroleum-derived asphalt. Additional advantages are found in the inclusion of dextrin in the "carbon additive". The amount of dextrin can vary from 1% to 10% as a percentage by weight of the "carbon additive". It should be noted that dextrin has previously been used as a component of sand molding media for steel castings. The sand molding means for steel are distinguished from the iron molding means for iron in that the mold does not have a carbon content. The function of dextrin in the present invention is to further increase the compactability of the sand molding medium, while at the same time increasing its plasticities in wet and dry. These purposes are achieved in the specific range of 1% -10% of the "carbon additive". In contrast, when dextrin is used in the sand molding media for steel, the function of the dextrin varies in that its purpose is to improve the castability of the sand molding medium in which it is incorporated and / or the amounts of dextrin used. They are substantially higher. Finally, it will be pointed out that the constituents of the sand molding means for iron are expressed herein, as a reason of convenience, in terms of a first medium comprising sand and a "pre-mix" in a given range of proportions; the premix is then defined as comprising a clay component and a carbon component in an established range of proportions; the carbon component is then defined in terms of a component of marine mineral carbon and a component of "carbon additive", also in a given range of proportions; finally the component of the "carbon additive" is defined in terms of a supplementary carbon source (water-soluble uintaite in the case of the present invention) and other optional components. This type of definition is used in view of the fact that a "pre-mix" is an article of commerce, which is normally purchased by a smelter to be mixed with sand purchased locally in the preparation of a sand molding medium for iron. A "pre-mix" can also be used as a "complement" constituent in the recycling of iron sand molding media. Similarly, the "carbon component" or "coal additive" could be purchased separately by a smelter to be mixed with independently acquired clays and / or marine coal in the formulation of a "premix" or they could be added separately as constituents of "complement" to independently control the ratios of carino / uintaite mineral coal miscible with water / clay. The scope of the present invention is not limited to the separate formation of the "carbon additive", "carbon component", "premix" for the purpose of providing a sand molding means. That is, the various constituents, in appropriate amounts, could be mixed together in a container to form a sand molding means of the present invention. In a further description of the present invention, several specific examples will be given. Each example comprises a batch of sand molding means for use in the formation of molds to be used in the emptying of iron articles. The batches of the sand molding means in various examples have communalities, which facilitates an appreciation of the improvements of the present invention. With the exception of two lots, the total weight of each batch of the sand molding medium is 9,072 kg (20 pounds). The exceptions are found in Examples 1A and 2, each of which has a weight of 6,803 kg (15 pounds). Each batch is comprised of a "premix" that includes a "clay component" and a "carbon component". The "clay component" comprises 7% of the total weight of the lot, 635 grams (1.4 pounds) for the lots of 9,071 kg (20 pounds) and 4-76 grams (1.05 pounds) in the lots of 6,803 kg (15 pounds) . The "clay component" also has the communality that each comprises 50% southern bentonine clay (also known as montmorilo-nite) and 50% western bentonia clay. Southern bentonia originates from natural clay deposits in the Sandy 'Ridge, Alaba a region and is characterized by aluminum silicates in which calcium is the main bound ion. Western bentonite originates from natural arilla deposits in the Colony region of Wyoming and is characterized by aluminum silicates in which sodium is the principal bound ion. These clays have been used for a long time in sand molding media and their effectiveness is well proven. In each of the examples if the batch balance is required, the "pre-mix" is added and is also comprised of common # 410 sand. The sand and the "premix" are combined to form the sand molding medium for the example. In each example water was added in the amount of some 1.0% -2.0% by weight of the sand molding medium to wet the medium to bring it to a wet state. The wet sand molding medium of each example was then tested to determine its objective physical characteristics of "wet plasticity", "dry plasticity" and "permeability". These characteristics were determined following the testing procedures established by the American Foundrymen's Society. In each example, the sand molding means, in its wet stage, was molded into a plurality of cylinders having a diameter of 5.08 cm (two inches) and a height of 5.08 cm (two inches). The cylinders were compacted at different densities to provide samples weighing 150 grams »155 grams, 160 grams and 165 grams. The following test procedures were then performed: AFS 202-87-S Compression Plasticity in 2 2 Wet (kg / cm (pounds / inch) AFS 203-87-S Dry Compression Plasticity (kg / cm 2 (pounds / inch2) AFS 203-87-S Mold Permeability (Proportional flow rate for counting) A diagram is provided for each example, which gives the plasticities and permeabilities for the different densities of the samples tested.

Example 1 The first example provides a reference point for a basic sand molding means comprising only sand and a clay additive.

For purposes of terms of reference, a sand molding means is defined as comprising a "Pre-mix", which is added to the basic sand component. In this benchmark example, the premix comprises 100% clay. The composition of the lot was: Lot 1 Percent Grams Pounds Sand 93.0 8454 18.6 Pre-mix 7.0 635 1.4 Pre-mix: Clay ^ 100.0 635 1.4 50% southern bentonite obtained from natural clay deposits in the Sandy's Ridge region, Alabama; 50% of western bentonite obtained from clay deposits in the Colony region, yoming.

The results of the objective test were: Weight (g) Plasticity in Wet Plasticity in Dry Permeability (kg / cm (psi)) (kg / cm (psi)) 150 0.4845 (6.9) 0.4915 (7.0) 415 155 0.5636 (7.6) 0.9128 (13.0) 333 160 0.7864 (11.2) 1.1937 (17.0) 255 165 1.0954 (15.6) 2.0363 (29.0) 209 It is well known that the sand molding medium, without a carbon additive, is not suitable for the melting of iron. These examples provide a baseline against which the effect of the carbon additives can be judged. That is, this reference line illustrates the plasticities and permeability of a given clay additive. An acceptable carbon additive would cause, in the worst case, a minimal decrease in the wet and dry plasticities, as well as a minimum decrease in the permeability of a sand molding medium in which it is included. Ideally, the carbon additive would increase in at least one of these objective characteristics, and, ideally, increase the totality of these characteristics. The examples will show that increases in both the wet and dry plasticities can be obtained by the carbon additives of the present invention.

Example 1A The purpose of this example is to provide a reference baseline for the characteristics of a conventional sand molding environment where marine mineral coal is the only source to provide the elemental graphite needed for iron smelting. It will be noted that in this and all the remaining examples herein, the "premix" comprises a "clay" component and a "carbon component". In this example, the "carbon component" is comprised of 100% marine mineral carbon.

Lot 1A Percent Grams Pounds Sand 91.25 6210 3.69 Preblend 8.75 595 1.31 Preblend: Component of Arilla ^ 80.0 476 1.05 Component of Coal 20.0 118.26 Component of Coal: Coal ore 100.0 118.26 See example 1 The lot is moistened to form a wet sand molding medium that was then molded into cylinders for the realization of the objective characteristics. The sand molding medium of this example was manipulated and was compactable in the manner that is normal to me? associated with the formation of molds for the iron fund. The results of the objective tests were: Weight (g) Plasticity in Wet Plasticity in Dry Permeability 2 2 kg / cm (psi) kg / cm (psi) 150 0.4213 (6.0) 1.0392 (14-8) 118 155 0.5968 (8.5) 1.8467 (26.3) 93 160 0.9058 (12.9) 2.5629 (36.5) 73 165 1.1796 (16.8) 3.3283 (47.4) 59 Example 2 This example illustrates the previously discussed use of an alternate carbon source, in addition to marine coal in providing the source of elemental carbon that is necessary for the casting of iron. This is the means of sand molding, of the state of the art, current that the present invention seeks to improve.

Lot 2 Percent Grams Pounds Sand 91.15 6202 13.67 Pre-mix 8.85 602 • 33 Previous Mixture: Clay Component 79.13 476 1. 5 Coal Component 20.87 118 .263 Coal Component: marine mineral coal 80.0 + 88 0.197 additive 20.0 + 30.066 Additive: Asphalt emulsion * 100.0 30.0.066 solids (50.0) 15 .033 water (50.0) 15 .033 emulsifier ** .1 .036 .00008 Emulsifier omitted p See Example 1. * Asphalt emulsion is a water emulsion of a pulverized asphalt derived from petroleum distillation and is commercially available of the Ashland Oil Company, Ashland, Kentucky, under the trademark BB2 +. The emulsion is formed at an elevated temperature, with the asphalt being in an over-cooled form at room temperature. ** The high molecular weight acrylic emulsifier is commercially available. available from the B.F. Goodrich, Calvert City, Kentucky under the trademark Carbopol 941-Due to the small amount involved, the weight of the acrylic emulsifier is not indicated in the total rounded weight of the carbon additive and the total weight of the batch. The same treatment of your weight is found in other examples.

The constituents of the additive were first mixed. The additive and the marine mineral coal were then mixed and then the clay component was added to form the premix. The premix is then combined in the sand component of the sand molding medium. For purposes of additionally providing a data reference line, the physical, objective characteristics of Lot 2 were determined as follows: Weight (g) Plasticity in Wet Plasticity in Dry Permeability kg / cm 2 (psi) kg / cm2 (psi) 150 0.3721 (5.3) 1.0883 (15.5) 118 155 0.5828 (8.3) 1.5799 (22.5) 95 160 0.8285 (11.8) 1.8537 (26.4) 72 165 1.1656 (16.6) 2.5489 (36.3) 58 The preliminary mix used in Lot 2 is a commercially available item. This means of sand molding is representative of what would be used in a typical foundry. The working characteristics (compactability, ease of handling, etc.) of this sand molding medium, which uses marine mineral coal and an additive that includes an oil-derived asphalt, as a source of supplementary coal, are well known. The inclusion of this additive also provides improvements in the characteristics of work on media in which marine coal is the only source of coal. The working characteristics of this batch are the reference line to appreciate the desired characteristics in the evaluation of the sand molding means provided by the present invention. It is also well known that, asphalt derived from petroleum, under the heat of molten iron, it decomposes to form a portion of the elemental iron necessary for the emptying of iron articles. In addition, when this additive (with an oil-derived asphalt) is used, the "complement" amounts of the "premix" are substantially reduced. It is additionally well established that benzene is emitted during this decomposition process.

Example 2A In the evaluation of supplementary, alternate coal sources for use in sand molding media, it is an accepted practice to omit the portion of marine coal from the coal component of the "premix" and replace instead a additional amount of clay. The data correlation is evident from Example 2A, which is equivalent to Example 2, but omits the marine mineral carbon content of that example. In fact, an additional amount of clay has been replaced by marine mineral coal. In this way, Lot 2A comprises: Lot 2A Percent Grams Pounds Sand 91.6 8400 18.52 Pre-mix 7.4 672 1.48 Pre-mix: Clay Component 94 - 6 636 1 .40 Coal Component 5 .4 36 .08 (1 00% Additive) Additive: Asphalt Emulsion * 1 00. 0+ 36 .08 solids (50. 0) 1 8 .04 water (50. 0) 1 8 .04 emulsifier ** .1 .036 .00008 + Emulsifier omitted # See Example 1; *, ** See Example 2 The constituents of this lot are mixed in the same way as in Example 2 and the following physical, objective characteristics were established: Weight (g) Plasticity in Wet Plasticity in Dry Permeability 150 0.4072 (5.8) 0.4213 (6.0) 410 155 0.5217 (8.0) 0.8777 (12.5) 330 160 0.7934 (11-3) 1.7554 (25.0) 242 165 1.1164 (15.9) 2.0363 ( 29.0) 203 The remaining examples set out formulations of sand molding media that teach additives that provide, at least, essentially the same advantages as the prior art, asphalt emulsion additives, while at the same time substantially minimizing, if not eliminating benzene emissions. In these examples (Lots 3-13) the marine mineral carbon component has been omitted and the respective examples have been evaluated on the basis of the "additive" alone, with respect to the example of the "additive" of the prior art in Example 2A . The manageability characteristics of Lot 3 (Example 3) were further evaluated by testing the sand molding media including marine mineral carbon to further verify that the physical and handleability characteristics of the additives without forecasting marine carbon will be observed when included marine coal.

Example 3 A batch of 9,071 kg (twenty pounds) (Lot 3) of sand molding medium with the following composition was prepared: Lot 3 Percent Grams Pounds Arena 92.6 8400 18.52 Pre-mix 7.4 672 1.48 Previous mixture: Clay Component ^ 94.6 636 1.40 Coal component 5.4 36.3 .08 (100% additive) Additive: uintaite powder *** 47.5+ 17.2 .038 water 47.5+ 17.2 .038 dextrin yellow color 5.0 1.8 .004 canary **** emulsifier ** .1. 036 .00008 Emulsifier omitted ß, t See Example 1; ** See Example 2 *** The Uintaita is a naturally occurring asphalt found in the Uinta River Valley in Utah, available from the American Gilsonite Company, Salt Lake City, Utah. The uintaite used in this and other examples herein was modified by the addition of a surfactant and identified as Gilsonite miscible with water.

**** Dextrin is a soluble polyscarcid obtained from starch. The designation "Yellow Carnario" is a type of designation, which indicates a high solubility in cold water. This dextrin is available from the National Starch Company, Indianapolis Indiana.

The components of the carbon component (additive) were completely mixed as a dispersion and then mixed with the clay component. The combined clay and carbon additives were then combined with the sand to form a sand molding medium (Lot 3). This means of sand molding, with a water content of 2.0%, was then formed into test specimens, which were tested in the manner described in the previous examples, with the following results: Weight (g) Plasticity in Wet Plasticity in Dry Permeability 2 2 kg / cm (psi) kg / cm (psi) 150 0.3581 (5 .1) 1 .0883 (15.5) 420 155 0.5266 (7. 5) 1 .6501 (23.5) 337 160 0.7864 (1 1 .2) 2. 5980 (37.0) 240 165 0.9900 (14 - 1) 3.5109 (50.0) 194 Laboratory tests were run on the uintaite, which showed that it was substantially free of benzene emissions when subjected to thermal decomposition, thereby confirming that an objective of the present invention had been met. The "additive" from Lot 3 was then used in more extensive field tests. A batch of several hundred kilograms (hundreds of pounds) (correct weight?) Was prepared for use in a smelter. The formulation of this larger batch was essentially the same as for batch 3, with the exception that the "carbon component" of the "premix" comprised 80% marine carbon and 20% the "additive" of mixed uintaite with water. This larger batch of sand molding medium was used in the formation of molds which were then used in cast iron casting. The manageability of the larger batch confirmed that its characteristics were at least equal to those possessed by the sand molding means that use "additives" based on asphalt, conventional. It was additionally determined that the plasticity / permeability characteristics were sufficient to allow the formation of mold cavities that produced suitable castings using the procedures normally employed in a conventional casting operation. Additionally, the larger batch test confirmed that handleability characteristics were as predicted by the "additive" only by proving that the handleability characteristics were at least good, and in some respects better than those produced when the additive was based on asphalt. based on oil. In addition, in the larger scale test, the sand molding medium was recycled, through the use of "pre-mix" add-on amounts. It was determined that minor amounts of "complement" premix were required, as compared to previous blends that do not include an additive. It was also determined that the amount of "complement" premix was approximately comparable to that required where the premix includes an oil-based additive. Additionally, in a smelter test of Lot 3 additive, the area was monitored for benzene emissions, and no amounts of benzene were detected.

Example 4 A batch of 9,071 kg (twenty pounds) (Lot 4) of the sand molding medium with the following composition was prepared: Lot 4 Percent Grams Pounds Arena 92.6 8400 18.52 Pre-mix 7.4 672 1.48 Previous mixture: M Clay Component ^ 94.6 636 1.40 Carbon Component 5.4 36.3 .08 (100% additive) Additive: uintaite powder *** 47.5+ 17.3 -04 water 47.5+ 17.3 -04 dextrin colored 5.0 1 *. 004 yellow canary **** emulsifier ** .1 .036 .00008 Emulsifier omitted See Example 1; ** See Example 2; ***, * - "- ** See Example 3 The components of Lot 4 are the same as in Lot 3. Lot 4 differed from Lot 3 in that the dry ingredients of the clay component and the carbon component (additive) were first mixed and combined. The water content was then added to this dry mix, providing a pre-moistened premix, as opposed to the dispersible additive of water-soluble uintaite which was first provided in Example 3. The pre-moistened premix was then mixed with the sand from the middle to form Lot 4 «This molding medium (Lot 4) > with a water content of 1.8%, then it was formed into test specimens, which were tested in the manner described in the previous examples, with the following results: Weight (g) Plasticity in Wet Plasticity in Dry Permeability kg / cm (psi) kg / cm (psi) 150 0.5196 (7.4) 0.7723 (11.0) 420 155 0.6460 (9.2) 0.8777 (12.5) 345 160 0.9404 (13.4) 2.3171 (33.0) 260 165 1. 1937 (17.0) 3.0193 (43.0) 210 The conclusion reached was that there was no significant difference in the formation of the "additive" as a water dispersion of the water-based uintaite with water or in the simple addition of uintain mixed with water in dry form to the clay component of the previous mixture.

Example 5 A batch of sand molding medium (Lot 5) with the same composition as Lot 3 of Example 3 > and in the same way, except that the high molecular weight acrylic polymer (Carbopol 941) was omitted.

Lot 5 Percent Grams Pounds Sand 92.6 8400 18.52 Pre-mix 7.4 672 1.48 Pre-mix: Clay Component ^ 94.6 636 1.40 Coal Component 20.0 36.3 .08 (100% additive) Additive: uintaite powder *** 47.5 17.3 .038 water 47.5 17.3 .038 dextrin colored 5.0 1.4 .004 canary yellow ***** in Example 1; ** **** See Example 3 This sand molding means (Lot 5), was appropriately wetted and then formed into the test specimens, which were tested in the manner described in the previous examples, with the following results: Weight (g) Plasticity in Wet Plasticity in Dry Permeability 2 2 kg / cm (psi) kg / cm (psi) 150 0.5757 (8.2) 0.5968 (8.5) 330 155 0.6951 (9.9) 1.1445 (16.3) 270 160 0.9549 (13.6) 1.7343 (24.7) 210 165 1.2639 (18.0) 2.2961 (32.7) 170 The results of this example confirmed the preference to employ an acrylic, high molecular weight emulsifier in the "additive". The manageability and objective test indicate that satisfactory sand molding means can be provided without this emulsifier. However, the handling characteristics, in particular, are improved when it is used.

Example 6 and 7 Examples 6 and 7 illustrate the effects of the variation of the amount of uintain in the carbon additive. In Example 3 the uintaite and water amounts were equal. In Examples 6 and 7, the total weight of uintaite and water was maintained the same, with a ratio of 1: 3 of uintain to water in Example 6 and a ratio of 3: 1 of uintaine to water in Example 7. In Example 6 a batch of 9,071 kg (twenty pounds) (Lot 6) of sand molding medium with the following composition was prepared: Lot 6 Percent Grams Pounds Arena 92.6 8400 18.52 Previous use 7.4 672 1.48 Previous mixture: Clay Component '94.5 636 1.40 Coal Component 20.0 36.3 .08 (1 00% additive) Additive: powdered uintain *** 23.75 8.6 .019 water 71.25 25.9 .057 colored dextrin 5 r -.0 r, + 1.8 .O04 yellow canary **** emulsifier ** 036 .00008 + Emulsifier omitted # See Example 1; ** See Example 2; ***, **** See Example 3 The components of the carbon additive were completely mixed as a dispersion and then mixed with the clay component to form the premix. This premix was combined with the sand to form a sand molding medium (Lot 6). This means of sand molding was then moistened to form test specimens, which were tested in the manner described in the previous examples, with the following results: Weight (g) Plasticity in Wet Plasticity in Dry Permeability 2 2 kg / cm (psi) kg / cm (psi) 150 0.6460 (9.2) 1.5447 (22.0) 387 155 0.8496 (12.1) 2.1767 (31.0) 305 160 1.1796 (16.8) 3.4406 (49.0) 230 165 1.4043 (20.0) 3.5109 (50.0) 188 In Example 7, a batch of 9,071 kg (twenty free) (Lot 7) of sand molding medium with the following composition was prepared: Lot 7 Percent Grams Pounds Arena 92.6 8400 18.52 Pre-mix 7.4 672 1.48 Pre-mixing: Clay Component 94.6 636 1.40 Carbon component 20.0 36.3 .08 (100% additive) Additive: uintaite. powder 23.25+ 25.9 .057 water 71.75 + 8.6 0.19 color dextrin 5.0 + 1.8 .004 canary yellow *** emulsifier ** .1 .036 .00008 + Emulsifier omitted # See Example 1; ** See Example 2; ***, **** See Example 3 These components were then combined, in the same way as in the previous example, to form a sand molding medium (Lot 7). Objective physical characteristics were determined as: Weight (g) Plasticity in Wet Plasticity in Dry Permeability kg / cm (psi) kg / sm (psi) 150 0.4072 (5.8) 0.2808 (4.0) 356 155 0.5125 (7.3) 0.6319 (9.0) 280 160 0.7864 (11.2) 1.2990 (18.5) 210 165 1.0392 (14-8) 2.3173 (33.0) 170 From a normal point of plasticity and permeability, both Lots 6 and 7 would satisfy the requirements for a sand molding medium. However, the reduced amount of uintaine miscible with water in Example 6, with a concomitant increase in both wet and dry plasticities, shows that reduced amounts of water-miscible uintain would be preferred, not only because of the economic advantage, but for the formation of molds that have thin-walled sections. The highest percentage of mixable uintaite with water used in Example 3 is still preferred in that the amount of uintaite mixed with water provides somewhat better handling characteristics.

Example 8-13 Examples 8-13 were provided to give a better understanding of the effects of dextrin on the sand molding media of the present invention. In Examples 8-13 a batch of 9,071 kg (twenty pounds) (Lot 8) of sand molding medium with the following basic composition was prepared: Basic Composition (Lots 8-13) Percent Grams Pounds Sand 92.6 8400 18.52 Pre-mix 7.4 672 1.48 Pre-mixing: Clay Component 94-6 636 1.40 Carbon Component 20.0 36.3 .08 (Additive) See Example 1; The composition of the additive was then varied for the batches of Examples 8-13. The batches of each of Examples 8-13 were formulated and tested in the same manner as Lot 3 of Example 3. Lot 8 has the same formulation as Lot 3, with the exception that the dextrin component is omitted, to provide a baseline on the effects of dextrin. In each of the remaining examples (9-13) the amount of dextrin was increased in 2% increments. In Example 8, the composition of the "additive" was: Additive - Lot 8 Additive: uintaite powder *** 50.0+ 18.15 .04 water 50.0+ 18.15 .04 emulsifier ** .1 .036 .00008 Emulsifier omitted # * See Example 2; *** See Example 3 Additive - Lot 9 Additive: uintaite powder *** 49.0+ 17.79 .0392 water 49.0+ 17.79 .0392 color dextrin 2.0 .72 .0016 canary yellow **** emulsifier ** .1 .036 .00008 Emulsifier omitted ** See Example 2;, ***, **** See Example 3 Additive - Lot 10 Additive: uintaite powder *** 48.0+ 17.43 .0384 water 48.0+ 17.43 .0384 color dextrin 4.0+ 1.44 .0032 yellow canary **** emulsifier ** .1 .036 .00008 Emulsifier omitted ** See Example 2; ***, **** See Example 3 Additive - Lot 11 Additive: uintain powder *** 47.0+ 17.07 .0376 water 47.0+ 17.07 .0376 dextrin color 6.0+ 2.16 .0048 yellow canary **** emulsifier ** .1 .036 .00008 Emulsifier omitted ** See the Ej. 2; ***, **** See Example 3 Additive - Lot 12 Coal Component: uintaite powder *** 4 477..55 1 6.71 .0368 water 47. 5 + 1 6.71 .0368 dextrin colored 5.0+ 2 .88 .0064 yellow canary **** emulsifier ** .1 .036 .00008 Emulsifier omitted ** See Example 2; ***, **** See Example 3 Additive - Lot 13 Coal component: uintaite powder *** 45.0+ 16.35 .036 water 45.0+ 16.35 .036 dextrin color 10.0+ 3 .6 .008 yellow canary **** emulsifier ** .1 .036 .00008 Emulsifier omitted ** See Example 2; ***, **** See Example 3 The objective physical characteristics of Lots 8-13 were determined to be: Plastic Weight ad in Mojad; _ Dry Plasticity Permeability (g) kg / cm (psi) kg / cm2 (] DSÍ) Ex. 150 0.5687 [8.1) 0.8426 '12 .0) 433 8 155 0.7864 [12.2) 1.8958 '27 .0) 326 160 1.0673 '15 .2) 2.5980 '37 .0) 259 165 1.3832: 19.7) 3.3704 '48 .0) 202 Ex. 150 0.6108 [8.7) 0.4564 [6.5) 403 9 155 0.8145: 11.6) 0.9479 [13.5) 223 160 1.2147: 17.3) 1.7554 [25.0) 237 165 1.4675 [20.9) 1.9661 [28.0) 199 Ex. 150 0.5687 (8.1) 1.1234 [16.0) 418 155 0.7864 [11.2) 1.5447 [22.0) 320 160 1.1445 (16.3) 2.4225 [34.5) 242 165 1.4113 [20.1) 2.7736 [39.5) 198 Ex. 150 0.6249 [8.9) 0.7021 [10.0) 408 11 155 0.8636: 12.3) 1.4043 [20.0) 317 160 1.0883: 15.5) 2.1767 [31.0) 240 165 1.3130: 18.7) 2.3523 [33.5) 200 Ex. 150 0.6083 [8.6) 0.8777 [12.5) 389 12 155 0.7794 [11.1) 1.4043 [20.0) 308 160 1.0602 [15.D 2.4576 [35.0] 229 165 1.3692 [19.5) 2.9491 [42.0) 192 Ex. 150 0.7723 [11 -0) 1.3692 [19.5) 345 13 155 0.9830 I [14-0) 2.1065 ('30 .0) 276 160 1.3973 < [19.9) 3.4406 ('49 .0) 207 165 1.6431 < '23 -4) 4.1779 (59.5) 170 The objective characteristics and manageability of the lots using the various concentrations of dextrin were all found to be acceptable and could be satisfactorily used in a smelting operation. However, the higher concentrations (Lot 13 in particular) reduce the permeability to a degree that could possibly cause a problem. Therefore, moderate concentrations and particularly the concentration of 5% of the preferred composition in Example 3. Variations of the precise compositions of the sand molding means were set forth in the examples, therefore, the limits of the invention are set forth in the following claims. Having thus described the invention, what is claimed as new and desired to be insured by Letters Patent of the United States is: It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates. Having described the invention as above, property is claimed as contained in the following:

Claims (9)

1. A sand molding means comprising, on a dry basis: silica sand 85% -95% pre-mix 5 -15% where the premix comprises: a clay component .... 70% -80% a Carbon component 15% -30% characterized in that the carbon component includes uintaite mixed with water.

2. A sand molding means in accordance with claim 1, characterized in that the carbon component comprises: marine or marine mineral coal. . . .25% -85% carbon additive 1 5 -75% and the carbon additive includes uintaite mixed with water.

3. A sand molding means according to claim 2, characterized in that the carbon additive comprises: a dispersion of the uintaite mixed with water.

4. A sand molding means in accordance with claim 3, further characterized in that the carbon additive comprises: uintaite mixable with water 25% -100% water (emulsified with uintaite) 0% -50% dextrin 0% -10% acrylic emulsifier of high molecular weight 0% - .2%

5. A sand molding means according to claim 4 further characterized in that the carbon additive substantially comprises the following: water-miscible uintaite 47.5% water (emulsified with uintaite) 47.5% dextrin 5% acrylic emulsifier with high molecular weight 0.1%

6. A premix for use in the preparation of a sand molding medium for iron casting wherein the sand molding means comprises on a weight basis: silica sand 85% -95% premix 5% -15 % wherein the premix comprises: a 70% -85% clay component, a 15-30% carbon component characterized in that the carbon component includes uintaite mixed with water.

7. A premix according to claim 6, characterized in that the carbon component comprises: marine or marine mineral coal 25% -85% 15% -75% carbon additive and the coal additive includes the water-mixable uintaite.

8. A premix according to claim 7, characterized in that the carbon additive comprises: a dispersion of the uintaite mixed with water.

9. A premix according to claim 8, further characterized in that the carbon additive comprises: uintaite mixable with water 25% -100% water (emulsified with uintaite) 0% -50% dextrin 0% -10% high weight acrylic emulsifier molecular 0% - .2% 1 0. A pre-mix according to claim 9, further characterized in that the carbon additive substantially comprises the following: water-mixable uintaite 47.5% water (emulsified with uintaite) 47.5% dextrin 5% high molecular weight acrylic emulsifier 0.1 %