US1825756A - Process of briquetting finely divided coal, fuel, or other pulverulent materials - Google Patents

Description

Patented Oct. 6, 1931 UNITED STATES PATENT OFFICE OTTO REYNARD, OF LONDON, ENGLAND PROCESS OF BRIQUETTING FINELY DIVIDED GOAL, FUEL, OR OTHER PULVERULEINT MATERIALS No Drawing. Application filed March 15, 1928, Serial No. 262,059, and in Great Britain April 4, 1927.

When finely divided coal or other fuel is briquetted with coal tar pitch or petroleum asphalt in the manufacture of briquettes, suflicient binding material has to be used to 5 cover all the particles of the material to be briquetted with a film of molten binding agent.

' It is a matter of experience that from 7 to 10 per cent of bituminous binding mateio rial has to be utilized to obtain satisfactory results, whereas it is a matter of calculation that less than 5 per cent is theoretically necessary to cover the entire surface of the fragmentary fuel with the molten binder, taking into consideration the average size of the fuel particles and the viscosity of the molten agglomerant under normal working condition. The excess of binder required is due to the inadequate wetting of fuel by molt- 2 en binder in ordinary practice, and results 1n a briquetted product which softens unduly and gives rise to unnecessary smoke when it is eventually consumed in a furnace.

The object of the present invention 1s to 135, provide means for improving the quality of the finished product and reducing the quantity of bituminous binder employed to the amount which is theoretically necessary and is carried out as follows The fuel is intimately mixed with from 3 to 6 per cent only of its weight of bitumlnous binder and before being introduced into the heated incorporatings-yessel, commonly known as the pugmill, there is added to 1t an aqueous emulsion which compnses:

1. An oil which has a natural aflinity for the bituminous binding agent employed; and

2. An emulsifying agent which is capable of forming reasonably stable emulsions with the-aforesaid oil, and which is itself preferablythough not necessarily-a substance possessing adhesive properties.

The emulsions which are suitable for the invention are of the water-in-oil type. The object and effect of adding such emulsions to a mixture of fuel and bituminous binding material is twofold. First, the oil ingredient of the emulsion fluxes the bituminous base to 59 form a product of lower melting point and agents for finely divided viscosity so that a harder pitch or asphalt than could be used alone becomes available for briquetting, with consequent increased ease ofgrmding and incorporating with the pulverized fuel. Secondly, the emulsifying agent, which will generally be an aqueous solution, but which may also be a pseudosolution or a suspension in water, induces the dispersion of water in the asphalt or pitch, which is fluxed by the oil, when the emulsifying agent comes into contact with bitumen at a temperature of 80 to 100 0., which is the normal range of temperatures to which the fuel and binder are heated in the final mix ng process. This dispersion of. water in bitumen is an essential feature of the present invention and results in increasing the volume and covering action of the agglomerant, which is thus compounded in situ during the final incorporation.

It has previously been proposed by various means, (a) to disperse water in a bituminous base, or b) to emulsify bitumen in water, and to use these compounded products as binding fuels, but the present invention diifers materially from these known processes. As regards (a), is special plant required to prepare such dispersions of water in bitumen, butthe resulting products are semi-solids which are tacky and diflicult to grind; moreover, they lose much of their essential dispersed water in the course'of grinding.

Further disadvantages attending the use of such compounded binders, are the very considerable costs'in power, labour, and plant upkeep which they entail, and the long period which must elapse between the time when the hot, plastic mass is first manufactured and the time when it is sufficiently cool and consolidated to go through a disintegrating appliance without choking it.

As regards (b), the products which are known as bitumen emulsions are emulsions of bitumen in water in which the water represents the continuous phase of the emulsion. Such emulsions cannot be produced by the methods of the present invention, which cause the dispersion of water in bitumen with the bitumen representing the continunot only ous phase, of the emulsion, which is momentarily produced when the various ingredients are brought together and heated in the final mixer. Furthermore an essential condition of emulsifying bitumen in water is the use of bitumen which melts at about or below the boiling point of water, whereas an important feature of the present invention is the use of bitumens which melt at and above 120 C. and which are quite incapable of yielding emulsions in water by any known process.

It is therefore clear that the present invention does not refer to the use either of a previously manufactured dispersion of water in bitumen or of a previously manufactured emulsion of bitumen in water, but refers solely to the use of emulsions of oil and water which are added to a mixture of finely divided fuel and a bituminous material.

Mixtures of oils with solidifying or saponifying agents have been added to fuel or road metal and pitch or other bituminous binding materials.

Emulsions suitable for the purpose oft-he present invention can be made i1rvar1ous ways, but these can be subdivided into two principal classes:

Class 1. Emulsions of water in oil are produced by the gradual addition with thorough agitation in an emulsifying vessel, of any one or more of the following substances, pre viously dissolved in water, to heavy petroleum fuel oil, which may possess either an asphaltic or a paraflin base: the chlorides, sulphates, nitrates, carbonates, or hydroxides of the alkali metals or of ammonia; the chlorides or nitrates of the alkalineearth metals; the silicates of the alkali metals.

Class 2. Emulsions of water in oil are produced by the same method as in Class 1, but instead of using solutions of mineral or inorganic salts, organic, colloidal solutions or suspensions are employed which possess a high degree of viscosity and which are themselves mostly substances possessing adhesive properties. Typical emulsifying solutions are those of sodium caseate, gelatin or glue, sodium alginate, sodium pectate, sodium tannate or cellulose sulphite waste liquor, either in the acid state or after neutralizing with caustic soda. Typical emulsifying suspensions are the pulps produced by boiling, preferably under pressure, cereals, such as maize, wheat, or barley, or tubers, such as potatoes or beet, or vegetable growths, such as marine or fresh water algae, with sodium carbonate or sodium hydroxide.

The emulsions in question will generally comprise one part of fuel oil to from one to six parts by weight of aqueous solution or suspension, and the manner in which the invention is carried out for the purpose of briquetting finely divided fuel, is as follows The fuel is intimately mixed with from 3 to 6 per cent of its weight of native asphalt, petroleum asphalt, or other pitch resultmg from the distillation of tars or mineral o ls. This intimate mixture may take place either by previously grinding the said asphalt or pitch or by adding the latter in a molten condition. After this intimate mixture has taken place a quantity of emulsion, representing from one to four per cent of the weight of the fuel is added to the mixture. Both the mixture of fuel with binder and the added emulsion may at this stage be cold. The addition of the liquid or pasty emulsion s made in such a manner that the emulsion 1S distributed throughout the mass of fuel as uniformly as possible in the first instance and the three constituents, fuel, bitumen and emulsion, may then be subjected to a further cold rmxing process in an appliance such as a squirrel cage or other form of mechanical mixer or homogenizer, before passing into the final mixer in which heating takes placeprior to briquetting.

E mample 1 Anthracite was briquetted with 6% B1 petroleum asphalt, melting point 120 (1., 12% of emulsion comprising equal parts by welght of Mexican fuel oil and a 20% soda ash solution.

Example .6

Anthracite was briquetted with 6% B1 petroleum asphalt, melting point 120 C.. 1.8% of emulsion comprising one part of Mexican fuel oil to two parts of a 5 11 solution of sodium caseate.

Example l l elsh steam coal was briquetted with 5% petroleum asphalt, m ng point l-l0 6.,

of emulsion compris n equal parts of mean fuel oil and 2% sodium alginate sciution.

E a'a/mple E wample 5 New Zealand Slack was briquetted with 6% B1 petroleum asphalt, melting point 120 C., 1.8% of emulsion comprising equal parts of Mexican fuel oil, cellulose sulphite waste liquor of 1.3 specific gravity, and water.

All the above examples gave briquettes, pressed at 30 cwt. to the square inch, which posesssed cohesions as determined by the Belgian drum test of from 85 to 90 per cent.

I claim novelty for a process of briquetting in which I bring together, during the stage when the constituents are incorporated and heated, immediately before they are moulded and pressed l. The fuel which is to be briquetted;

2. lhe bituminous material-which is the binding agent;

3. An emulsion-which serves solely to increase the activity and efliciency of (2).

I do not claim the emulsions (3) as binding agents, which, for the most part, they are not.

ll do not claim that all the emulsions which I may use are novel, though most of them are.

What I claim is the method whereby the emulsions (3), applied in the manner I described, cause a dispersion of Water 1n (2) at the moment when the mixture is prepared for briquettingsuch dispersion increaslng the covering power, and therefore the cement ng action; of the binding agent (bitumen) whlch is employed.

It is an esential feature of my invention that the emulsion should persist unbroken and in its original liquid form until such time as it has been added to the mixture of fuel and binding agent.

l claim 1. A process of briquetting cons1st1ng 1n mixing a finely divided pulverulent material and a solid bituminous material and adding thereto an emulsion of the water-in-oil type comprising an oil having an aflinity for the bituminous material and an emulsifying agent capable of forming stable emulsions with the oil, and subsequently heating and pressing the mixture.

2. A process of briquetting consisting in mixing a finely divided pulverulent material and a solid bituminous material and adding thereto an emulsion of the water-in-oil type e comprising an oil having an aflinity for t bituminous material and an emulsifying agent possessing adhesive properties and capable of forming stable emulsions. with the oil, and subsequently heating and pressing the mixture.

3. A process of briquetting consisting in mixing a finely divided pulverulent material and a solid bituminous material normally melting at and above 120 C. and adding thereto an emulsion of the water-in-oil type comprising an oil having an aflinity for the bituminous material and an emulsifying agent capable of forming stable emulsions with the oil, and subsequently. heating and pressing the mixture. v 4. A process of briquetting conslsting in mixing a finely divided pulverulent material and a solid bituminous material and adding thereto an emulsion of the water-inoil-type comprising one part of an oil having an affinity for the bituminous material and one to six parts by weight of an emulsifying agent capable of forming stable emulsions with the oil, and subsequently heating and pressing the mixture.

5. A process of briquetting c0nsisting in mixing in a cold state a finely divided pulverulent material and from three to six per cent of its Weight of a solid bituminous material and adding thereto from one to four per cent of its weight of an emulsion of the water-in-oil type comprising an oil having an aifinity for the bituminous material and an emulsifying agent capable of forming stable emulsions with the oil, and subsequently heating and pressing the mixture.

6. A process of briquetting consisting in mixing a finely divided pulverulent material and a solid bituminous material normally melting at and above 120 C. and adding thereto an emulsion of the water-in-oil type comprising an oil having an aflinity for the bituminous material and an emulsifying agent possessing adhesive properties and capable of forming stable emulsions with the oil, and subsequently heating and pressing the mixture.

7. A process of briquetting consisting in mixing a finely divided pulverulent material and a solid bituminous material normally melting at and above 120 C. and adding thereto an emulsion of-the water-in-oi'l type comprising one part of an oil having an affinity for the bituminous material and one. to six parts by weight of an emulsifying agent possessing adhesive properties and capable of forming stable emulsions with the oil, and subsequently heating and pressing the mixture.

8. A process of briquetting consisting in mixing in a cold state a finely divided pulverulent material and from three to six per cent of its Wei ht of a solid bituminous material and adding thereto from one to four per cent of its weight of an emulsion of the water-in-oil type comprising an oil having an affinity for the bituminous material and C. and addingmixing in a cold state a finely divided pulverulent material and from three to six per cent of its weight of a solid bituminous material normally melting at and above 120 C. and adding thereto from one to four per cent of its weight of an emulsion of the water-inoil type comprising an oil having an affinity for the bituminous material and a emulsifying agent capable of forming stable emulsions with the oil, and subsequently heating and pressing the mixture.

11. A process of briquetting consisting in mixing in a cold state a finely divided pulverulent material and from three to six per cent of its weight of a solid bituminous 1naterial and adding thereto from one to four per cent of its weight of an emulsion of the water-in-oil type comprising one part of an oil having an ailinity for the bituminous material and one to six parts by weight of an emulsifying agent capable of forming stable emulsions with the oil, and subsequently heating and pressing the mixture.

12. A process of briquetting consisting in mixing in a cold state a finely divided pulvernlent material and from three to six per cent of its Weight of a solid bituminous material normally melting at and above t2U (l. and adding thereto from one to four per cent of its weight of an emulsion of the water-inoil ty )e comprising one part of an oil having an a nit-y for the bituminous material and one to six parts by weight of an emulsifying agent capable of forming stable emulsions with the oil and subsequently heating and pressing the mixture.

13. A process of briquetting consisting in mixing in a cold state a finely divided pulverulent material and from three to six per cent of its weight of a solid bituminous material normally melting at and above 120 C. and addin r thereto from one to four per cent of its weig it of an emulsion of the water-inoil ty comprising one part of an oil having an a nity for the bituminous material and one to six parts by weight of an emulsifying agent possessing adhesive properties and capable of forming stable emulsions with the oil and subsequently heating and pressing the mixture.

In testimony whereof I have hereunto set my hand this 5th day of March. 1928.

a OTTO REYNARD.