US2318555A

US2318555A - Cleansing agent and the

Info

Publication number: US2318555A
Authority: US
Publication date: 1943-05-04
Anticipated expiration: 1960-05-04

Description

May 4, 1943- R. F. RUTHRUFF 2,318,555

CLEANSING AGENT AND THE MANUFACTURE THEREOF Filed Jan. l5, 1940 CYCL 0/14.F 5MM/Wm INVE R Patented Mey 4, 1943 CLEANSING AGENT AND MANUFACTURE THEREOF I tobert F. Ruthmfl, Chicago,'lll. Application January 15, 1940, Serial No. 313,899

7 Claims.

This invention relates to an abrasive detergent and a process for the manufacture thereof. More particularly, this invention relates to a material having a combined detergent and abrasive action and a process for fthe manufacture thereof. Specifically, this invention relates to a material comprising a superficial iayer of alkali metal silicates formed upon the surface of a siliceous particle and a process for the manufacture thereof, said material exhibiting a combined abrasive and detergent action. Y

The detergent action of various alkali metal silicates has been known for a number of years. For example. various alkali metal silicates have been employed in the compounding of soaps for at least 75 years. Similarly, the addition of abray sive agents such as finely divided pumice iodetergents to increase the effectiveness of the latter is well known in the art. However, as far as I am aware, no one has previously suggested an abrasive-detergent combination in which these two elements are combined in a single whole that initially exhibits a high detergent action which as it declines is gradually replaced by an increasingly severe abrasive action.

One object of the instant invention is to provide an improved cleansing agent and a method for producing the same. A further object. of this invention is to provide a cleansing agent exhibiting initially a high detergent action which progressively declines during use and a method for producing the'same. Another object of this invention is to provide a cleansing agent exhibiting 'initially a low abrasive action which progressively increases during use and a method for producing the same. An additional object of this invention is to provide a cleansing agent exhibiting an initially high detergent action which progressively declines during use and is simultaneously replaced by a progressively increasing abrasive action and a method for producing the same. Another object of this invention is to particleslincreases. so that while Ithev detergent provide an improved cleansing agent by a continuous process. Further objects of this invention will become evident from a perusal of the instant specification.

Briey, my invention embraces a material comprising a siliceous core with a superficial coating orv glaze of alkali metal silicates formed thereon s and a method for producing such a material. As is well known to those skilled in the art, alkali metal silicates may be prepared by fusing a mixture of siliceous material and alkali metal carbonate or a mixture of siliceous material, a1- kaii metal sulfate, and carbon at high temperatures. By this means alkali metal silicates of varying alkali'metal oxide-silicate ratios may be prepared. When sodium compounds are used. sodium silicates having ratios of from 1:1 to 1:4.2, more or less, may be formed, material having a ratio of 1:3.4 being especially common and widely used. In accord with the teachings of my invention, discrete particles of siliceous material are reacted by a method -and means to-be described in detail subsequently so that.

the reaction product comprises discreteparticles. each taking the form of a core of siliceous material bearing a layer or glaze of alkali metal silicates formed thereon. The outermost layers of the resulting particles consist of highly alkaline silicates; -the alkalinity decreases progressively as the center of the particle is approached until the unchanged siliceous core is reached. It is obvious that when these discrete particles are used in conjunction with water to clean surfaces by the well known techniques employed with cleansing powdersof the prior art, a gradual change in action is exhibited. Initially, by solution of the outermost layers, a highly alkaline detergent solutionls produced, but due to the softness of the outer surfaces of the discrete particles the abrasive action is nil or practically so. As the cleaning operation is continued, the

silicates removed from the surfaces of the discrete particles become progressively less alkaline, but simultaneously the surface hardness of these action decreases the abrasive action increases. Theoretically, when all alkali metal silicate has been 'removed from the outer surfaces of the discrete particles, a core of siliceous matter remains, which. while incapable of furnishing further material of detergent properties to the liquid medium, is extremely hard and has a high abrasive action.

The improved cleansing agents of the instant invention are particularly suited for cleaning surfaces which can stand a reasonable amount of abrasion lwithout harm. Among such suitable uses may be mentioned the cleaning of heavy duty floors, for example garage floors, machine shop floors, chemical plant floors and the like, the cleaning of decks, the cleaning of grease and scale from steel sheet. castings, forgings and the like prior to enameling, painting or similar treatment. the 'cleaning of metal surfaces in general, and the removal of dirt and grime from buildings, monuments and other structures.

As has been mentioned previously, alkali metal silicates are largely prepared by fusing a mixture of a siliceous material and alkali metal carbonate or by fusing a mixture of siliceous material, alkali metal sulfate and carbon. These fusions are usually conducted batchwise in open hearth regenerative type furnaces, but reverberatory furnaces may be used. It is obvious that these methods may be applied to the manufacture of the improved cleansing agents of the Instant invention. For example, discrete particles of siliceous material may be given a superflcial adherent layer of alkali metal carbonate or of a mixture of alkali metal sulfate and carbon, the quantity of alkali metal salt used being insufcient to react with all of the siliceous material. On fusing such a reaction mixture as above described, a superficial layer or glaze of alkali metal silicates forms on the surface of the siliceous material. Unless under extremely careful control, during the fusion the discrete particles fuse together and defeat the objects of this invention. If large particles of siliceous material are employed. this fusing together may be largely overcome by careful control of the fusion process, and by lightly crushing the reaction product the particles that have coalesced may be disrupted. However, by using the apparatus of the prior art, the objects of this invention are usually accomplished only when siliceous material having a particle size larger than is ordinarily wanted is employed. When siliceous material having a particle size within the usually desired limits is employed, a. microscopically homogeneous fused mass results.

For the above reasons it is usually advisable to employ the method and apparatus now to be described, or suitable modifications thereof, in the manufacture of the improved cleansing agents of the instant invention. Briey, discrete particles of siliceous material of the desired particle size are given a superflcial coating of a sufficient amount ol material or materials capable of reacting at elevated temperatures with the siliceous substrate to form a superficial glaze or coating of alkali metal silicates thereon. The resulting material is suspended in a moving stream of highly heated gas for a period sufflcient for such interaction to occur. If necessary for the reaction, the highly heated gas may have a reducing action. After reaction, the products are separated from the gas stream by known wherein the gure is a diagrammatic representation, partly in section and partly in elevation, of a suitable apparatus for carrying out the process' of this invention.

In the figure, numeral I designates a reactor suitable for the purpose of this invention. It will be observed that this reactor takes the form of an elongated conduit having a slnuous conformation. The exact form and conformation of the reactor are largelymatters of choice; in the present instance the particular conformation lselected was chosen for the purpose of keeping the height `of the reactor Within reasonable limits. In the particular embodiment pictured, the reactor I is supplied with hot gases from hot gas producer 2, which are introduced into the reactor I through line 3. Hot gas producer 2 is so constructed as to enable combustion to proceed therein at moderately elevated pressures, for example, pressures in the neighborhood of 45 pounds per square'inch if desirable or necessary.

When valves I and 8 are raised, communication between 5 and 6 is cut oil while 5 is open means are provided for heating the solid re` actants in bin or hopper 4. In the figure, this heating means takesthe form of a tubular heat exchanger in 6. Solid reactants flow through the tubes I0 in this exchanger while the tubes themselves are surrounded by suitable heated uid entering through line II and leaving through line I2.

Solid reactants are moved from hopper or bln 4 by means of screwr conveyor I3 or other similar suitable device and are thereby conveyed to re,- actor I. By using a properly designed screw conveyor, it is not absolutely essential to divide bin or hopper 4 yinto upper and

lower sections

5 and 6 separated by valve 8. Properly designed screw conveyors are able to seal against appreciable pressure so that I3 acts to prevent blow backs from reactor I through hopper 4. However, as a safety precaution, it is well to design hopper or bin 4 as described or in a similar fashion. If desired, solid reactants may be discharged by screw I3 into a Venturi throat I4 disposed in reactor I. By this means suspension of the solid reactants in the gases entering through 3 is greatly facilitated.

The suspension of solid reactants in the gases entering through line 3 passes through reactor I in which reaction occurs. The reaction products leaving reactor I are in av highly heated condition and should be cooled appreciably before being worked up. This may be accomplished by any suitable means, for example by spraying water into the suspension through line I5 or by passing the suspension over coils I6 through which water is owing 0r both.

Reaction products are now separated from the partially cooled suspension. This separation is usually accomplished in two steps. A rough separation occurs in the rst, while the greater part of the remaining reaction products is removed iii. the second. Any suitable separation means may be employed. In the ligure the use of a gravity separator and a cyclone separator in series is shown, but other separation means, for example Cottrell precipators, may be used. In the flgure, the partially cooled suspension is shown passing to gravity separator Il through line I8. In gravity separator I'l, the velocity of the suspension is much reduced and the direction of. flow is changed several times. Separated solids may be removed through lines I9. Partially separated suspension is sent from gravity separator I'I through line 20 to cyclone separator 2|, where practically complete removal of solid reaction products occurs. these being removed through line 22.

'The practically solid-free gas leaves cyclone separator 2l through line 23 and passes to air preheater 24, leaving through line 25. Part of the stream in line 23 may be diverted through line Ib to preheat solid reactants as previously described. Air enters air preheater 24 through line 26 and leaves through line 21, passing to` hot gas generator 2.

45 pounds per square inch. If desired or necessary, a suitable amount of gaseous, liquid or solid fuel may be introduced into the preheated air stream via line 28, this fuel then being partially or completely burned in hot gas producer 2.

As the suspension leaving reactor I contains appreciable sensible heat, it is advisable to recover` as much of this as possible in the form of useful work. This may be done in a number oi ways. For example, large amounts of steam may be generated in coil I8. Also, the hot gas may be used to drive a turbine, although it is preferably used for this purpose-only after the solids suspended therein have been removed. As shown in the figure, part of the heat content of the gas is recovered and used to preheat air while another part is devoted to preheating the solid reactants.

As temperature conditions are very severe in hot gas producer 2 and reactor I, these must be constructed with this in mind. It has been found that an inner layer of high grade refractory brick backed by two layers of fire insulating value, the whole being surrounded with sheet steel, constitutes an economic and satisfactory method for constructing hot gas generator 2 andreactor I. Line I5 and coil I6 are preferably made from 18-8 or similar high temperature alloy steel. The remaining parts of the apparatus may be constructed from alloy steel or ordinary mild steel.

While the reactor shown in the ligure consists of an elongated conduit of sinuous form having three legs in which the reactants rst pass upward, then downward and then upward again, this'particular conformation is illustrative only and in no way limits the scope of this invention. The number of legs possessed by the reactor and the direction of flow therein are immaterial. For example. instead of the reactor shown, equally satisfactory resultsv are obtained with reactors having one, two, four or more legs. Also, it is not necessary to introduce the reactants into an ascending leg of the reactor. Reactants, if desired, may be introduced into the upper portion of a descending leg and such reactors again may have one ormore legs. Also, while in the figure the reactor is shown disposed vertically, equally satisfactory results have been obtained using horizontal reactors or reactors with alternating vertical and horizontal legs.

The figure and the above'description relating thereto cover one embodiment of an apparatus suitable for the present invention. Further details, including quantities, temperatures, rates and the like, as well as a few of the many possible modifications of the apparatus shown and described will be outlined in the five examples to follow.

Eample 1 On hundred pounds of a high grade Ottawa sand of about 20 mesh size are uniformly coated with a strong solution containing 26 pounds of If desired, this air may be under low superatmospheric pressure, for example up to i between 2400 Fand brick of high sodium carbonate. 'I'he resulting mixture is slowly dried, preferably while being stirred, and is then charged into bin or hopper 4 of a semicommercial unit similar to that shown in the ligure. A natural gas comprising essentially methane is charged to the hot gas producer 2 through line 28 at a rate of about 17 cubic feet per minute: this-gas is burner in air introduced through line 21. In this modification of the general method for producing cleansing agents in accord with this invention, the hot gas stream may be inert, oxidizing or reducing in its action. For heat economy an inert hotgas stream is to be preferred; that is, the theoretical amount of air is introduced through line 21. Circulation is continued without introduction of solid reactant until the whole system is brought up to temperature, at which time screw I3 is started and the silica particles coated with sodium carbonate are introduced into the reactor at a rate of about 14.5 pounds per minute. Conditions are so regulated that the temperature in cyclone separator 2| is somewhat above 1000 F., while the temperature of the air in line 21 and the solid introduced into reactor I is somewhat above 850 F. As far as can be measured, the temperature in reactor I varies 2700 F., but little reliance can be placed on these determinations. The re-y actor employed has a cross sectional area of one square foot. Product is removed from lines I9 and line 22.

Eample 2 One hundred pounds of approximately 40 mesh Ottawa sand are coated with about 11 pounds o1' a 17.6 A. P'. I. petroleum stock representing 20% bottoms from Mid-Continent crude. Some 35 pounds of nely divided sodium sulfate is then thoroughly mixed. in and the Whole is then brought to dryness, while being heated in an inert atmosphere, preferably in a slowly rotating kiln or similar device. The resulting material is charged to hopper or bin 4 of an apparatus similar to that shown in the figure. A natural gas comprising essentially methane is charged at a rate of about 8 cubic feet per minute to hot gas producer 2 through line 28. This gas is burned in the presence of air introduced through line 2". In this modication` of the general method for producing cleansing agents in accord with this invention, the hot gas stream may be inert or reducing in its action. For heat economy it is advisable to operate using of air providing that combustion is perfect:

otherwise a slight deciency of air should be used to insure that the hot combustion gases contain no oxygen. Hot gas circulation is continued without introduction of solid reactants until the whole system is brought up to reaction described, is introduced into reactor I at a rate of about 5.5 pounds per minute. Temperatures are similar to those described in Example 1. Product is removed from lines I9 and line 22.

Example 3 In this example, as the hot gas is produced' the theoretical amount One hundred pounds of high grade Ottawa sand of about 20 mesh size are mixed with about 80 pounds of a 17.6 A. P. I. petroleum fraction representing 20% bottoms on Mid-Continent crude. Twenty-six pounds of sodium carbonate are added and the whole, after thorough mixing, is heated to drive off volatile matter. This may be accomplished, for example, by heating the material in an inert atmosphere in a slowly rotating kiln or similar device. The resulting material is charged to hopper or bin 4 of an appa-t ratus similar to that pictured in the figure. The whole apparatus is brought up to temperature by burning a suitable fuel in hot gas producer 2, following which this is gradually discontinued, solid reactants being simultaneously cut into reactor I by starting screw I3 while preheated air is added to line 3 from line 21 either by means of a bypass (not shown) or via hot gas producer 2. Under settled conditions the silica-carbonsodium carbonate mixture is added to reactor I at a rate about 14.5 pounds per mlnute,while preheated air is l added to line 3 at a rate of-about 175 cubic feet per minute, measured at standard conditions. Temperatures are similar to those quoted in Example l. Reaction products are removed from lines I9 and line 22.

Example 4 Again, in this example, hot gas is produced autogenously, so that hot gas producer 2 is not required except perhaps initially when it is Preferably used to bring the whole apparatus up to temperature. If desired, a bypass between line 21 and line 3 may be constructed so as to short circuit gas producer 2 when temperature has been achieved. One hundred pounds of high grade Ottawa sand of about 80 mesh are mixed with 110 pounds of a 17.6 A. P. I. petroleum fraction representing 20% bottoms from Mid-Continent crude. Following this, 35 pounds of sodium sulfate are added and after thorough mixing volatile matter is driven oil, for example, by heating the whole in an inert atmosphere lna slowly revolving kiln or similar device. The resulting material is charged to hopper or bin 4 of an apparatus similar to that shown in the ligure. The whole apparatus is brought up tof/temperature by burning a suitable fuel in hot gas producer 2, following which this is gradually discontinued, solid reactants being simultaneously cut into reactor I by starting screw I3 while preheated air is added to line 3 from line 21, either by means of a bypass (not shown) or via hot gas producer 2. Under settled conditions the silica-carbonsodium sulfate mixture is added to reactor I at a rate of about '7 pounds per minute, while preheated air is added to line 3 at a rate of about 85 cubic feet per minute, measured at standardconditions. Temperatures are similar to those given in Example l. Reaction products are removed from lines I9 and line 22.

Example One hundred pounds of high grade Ottawa sand of about 80 mesh is mixed with a strong solution containing 35 pounds of sodium sulfate. The mixture is then brought slowly to dryness,

. preferably with agitation, and is then charged ducer gas is at a temperature somewhat above 850 F. and preferably has a'low content of solids. Air is introduced into hot gas producer 2 through line 21 at a rate of 40-45 cubic feet per minute, measured atstandard conditions. The combustionvthat occurs Yin hot gas producer 2 soon brings the Whole apparatus up to temperature, at which time screw I3 is started and the sand-sodium sulfate mixture is added tothe reactor I at a rate of about 5 pounds per minute. Product is removed from lines I9 and line 22. Temperatures are approximately as specified in Example 1.

It is obvious that in all the above examples, once the unit is on stream operation is continuous. While in each of the above examples a suitable starting up procedure is described, it is to be understood that this is resorted to only on bringing a new apparatus on stream or when a new run is begun after a protracted shut-down for repairs, reconditioning or other reasons.

In each of the ve examples considered above, the solid reaction mixture is usually obtained in the form of lumps or aggregates of appreciable size. This is especially true in Examples 2, 3 and 4. Such lumps or aggregates not only are apt' to clog hopper or bin 4 and screw I3 but also they are difficult or impossible to suspend in the gas stream entering reactor I through line 3. For these reasons it is advisable to reduce these lumps or aggregates to suitable size before being introduced into hopper or bin 4. With the solid reaction mixtures formed in accord with Examples land 5, this is easily accomplished by gentle crushing, working through sieves, or by similar means. The solid reactant mixtures prepared in accord with Examples 2, 3 and 4 are usually obtained in the form of lumps exhibiting more or less porosity depending upon the exact conditions employed in removing volatile hydrocarbons. -These materials require crushing prior to charging to the hopper or bin 4. The exact size of the material to be charged depends upon the mesh size of the siliceous material employed and on the porosity of the carbonaceous matter. Ob-

"vio/usly, the ideal is aggregates each of which contains one silica particle.

While the use of' the carbonaceous material commonly known as petroleum coke or oil coke is described in Examples 2, 3 and 4, it is obvious that other suitable forms of carbonaceous material may be used. Preferably such material should have a low ash content. Other suitable materials for the formation of carbonaceous matter in accord with the teachings of Examples 2, 3 and 4 include molasses and coal tar pitches. Also, part of all of the carbonaceous lmatter may be added to the solid reactants in other ways. For instance, in Example 3, instead of proceeding as described, a silica-sodium carbonate mixture may be prepared in the proportions outlined in Example 1 and in the same or similar manner, and this may be mixed with about 10 pounds of petroleum coke, carbon black or low-ash coal and the whole charged to'hopper or bin 4. Similarly, in Example 4 a silica-sodium sulfate-carbon mixture may be made using the proportions of Example 2 and to this may be added 12-13 pounds of petroleum coke, carbon black, or lowash coal and the whole charged, after mixing, to hopper or bin 4.

The nature of the cleansing agent formed may be varied' appreciably by changing the contact time in reactor I. Obviously, changes in contact time can have little or no eil'ect on the analysis discrete f variable actions just of the products formed. but'it has been found that the distribution of components is affected to an appreciable extent. When contact time is short the products formed consist largely of discrete particles having a comparatively large silica. core bearing a comparatively thin superficial layer of alkali metal silicates having high alkalinity. Such materials when used as cleansing'agents tion which rapidlychanges to a high vabrasive action.- If, on the other hand. the contact time is long, the products formed consist largely of particles having a comparatively small silica core bearing a comparatively thick layer of alkali metal silicates having low alkalinity. Such materials when used as cleansing agents exhibit an initially moderate detergent action which slowly changes into an increasingly severe abrasive action.

It'is impossible to for the production of cleansing agents having the described. The proper contact times must be determined for each individual apparatus under a given set of operating conditions. This is true for several reasons. In the first place, temperature conditions are somewhat variable in the reactor and cannot be measured with any great degree of certainty. Also, the phenomenon of slip is encountered. While solid reactants may be added to the reactor at a certain constant rate, measured as pounds of solid per cubic foot of gas. the concentration of solids in the reactor space may be equal to this gure or manyfold greater depending on the gas velocity through the reactor. The solids concentration in the reactor space approaches that of the added solids at high air velocities. Thus, a reactor of cross sectional area X and length L may give a longer contact time than calculated and in some cases a contact time manyfold longer than calculated, while a reactor of area 0.25X and length 4L may give a contact time very close to calculated. Also, required contact time is a function of the material charged.. As a general rule. the silica-sodium sulfate system requires a longer reaction time .than the silica-sodium carbonate. Naturally. the contact time required to produce a cleansing agent of any desired set of properties also depends upon the size of the silica par ticles charged. While it is impossible to give any definite figures, it may be stated .that under the conditions outlined in Example l, a cleansing agent of average properties was obtained at a calculated contact time of 3 seconds.

While Ottawa sand has been specified as the siliceous material in the examples, numerous equivalents, for example, quartz, quartzite and diatomaceous earth, will readily occur to those skilled in the art. While sodium carbonate has been used in certain examples as illustrative of a material capable of reacting directly with siliceous material to form sodium silicates, many equivalents, such as sodium oxide. sodium peroxide, sodium hydroxide. and salts capable of forming one of these when thermally decomposed, may be substituted therefor. Likewise. equivalents for the sodium sulfate mentioned in some examples as illustrative of a compound that must be reduced prior to reduction with siliceous material will occur to those skilled in the art, while in the examples, sodium compounds have been cited exclusively. suitable compounds of other alkali metals may be used.

In the examples the silica material and sodium salt are so proportioned as to give an overall exhibit an initially high detergent acgive definite contact times4 prior to use.

I tate sodium `oxide-silica ratio of 1:6.8 calculated Jn the mole basis. Obviously, the instant invention is not limited to this ratio. this constant ratio being employed in the examples simply to facilicomparisons between the various processes. Ratios of `from about 1:3.5 up to 1:10 or more have been employed.

As has been previously mentioned, the cleansing agents of this invention are primarily for useln what may be termed heavy duty cleaning. Theoretically it should be possible to make these improved cleansing agents with the inertfsiiica core as small as desired, .so that the materials can e used in cleansing operations of higher order. Actually. however, this has been found diilicult to accomplish, due toa few unreacted or only partially reacted silica particles that are usually formed simultaneously with the desired y product.

After being formed it is advisable to keep the resulting products out of contact with air until used to prevent caking. his caking tendency may be reduced considerably by thoroughly steaming the products after being formed. The

-products of this invention may be incorporated with other detergent and/or abrasive materials Among suitable additional detergent agents may be mentioned soaps, alkali metal carbonates, alkali metal hydroxides, alkali metal pyrophosphates, alkali metal metaphosphates. and the like. Among abrasives may be mentioned pumice, sand, corundum, and the like. Also, if desired, inert materials may be added. A particularly effective cleansing agent may be made by coating the products formed according to the teachings of thisy invention with sodium hydroxide or with soap.

examples of various modifications thereof, it is to be understood that this apparatus and these examples are illustrative only and are included for the purpose of familiarizing those skilled in i mate range 3.5 to 1 to 10.0 to l.

2. A cleansing agent in the form of individual particles each of which consists of a silica core covered with an autogenous layer of sodium silicates, the silica to sodium oxide ratio of said individual particlesrange 3.5 to 1 to 10.0 to 1.

3. A process for the manufacture of a cleansing agent composed of silica particles coated with an autogenous layer of alkali metal silicates consisting of suspending, silica particles coated with alkali metals in a stream of combustion gases at elevated temperature for a time suiiicient to effect reaction between the selected coating mafalling Lin the approximatev of combustion gases.

5. A process in accordance with claim 4 wherein said stream of combustion gases is brought to reaction temperature by the combustion of carbonaceous matter contained in. saidcoating of sodium carbonate.

6. A process for the manufacture of a cleansl5 ing agent composed oi' silica particles coated with an autogenous layer of sodium silicates consisting of suspending silica particles coated with sodium sulfate in a stream of combustion gases at elevated temperatures for a time sumcient to eil'ect reaction between said sodium sulfate and the peripheral portions of the silica particles and separating the resulting product from said stream of combustion gases.

'7. A process in accordance with claim 6 wherey in said stream of combustion gases is brought to reaction temperature by the combustion otcarbonaceous matter contained in said coating oi' sodium sulfate.

ROBERT F. RUTHRUFF.