Elements of industrial chemistry

Preface

The purpose in presenting this elementary work on Industrial Chemistry is to meet the needs of those teachers of the subject who find that the time at their disposal does not warrant the employment of an extended treatise. The author, therefore, has compiled from the Manual of Industrial Chemistry an abridged volume which covers the most salient points of the larger book. The endeavor has been, in arranging this condensation, to treat the subjects covered in a general manner only, thus eliminating as much of the detail as possible in order that the fundamental principles might be more clearly set forth.

Although the subject matter is essentially descriptive, a certain amount of theoretical consideration has been included where necessary for the proper understanding of the text. Should the student desire more detailed information on the subject, or a more extended description of the processes under consideration he is referred to the Manual from which this book is compiled. No claim for originality is made for this volume, and full credit should be given to those who contributed to the larger book mentioned above.

The book as it now stands consists of twenty-seven chapters covering a somewhat limited range of subjects, but at the same time is sufficiently broad to give the student a very comprehensive view of the entire field.

Allen Rogers.

Pratt Institute, Brooklyn, N. Y.

September 20, 1916.

CONTEXTS

PAGE

General Processes Chapter I 1

Grinding — Crushing — Crushers — Mills — Disintegrator — Pulverizer — Sifting — Sedimentation — Levigation — Filtration — Filter Press — Centrifugal machine— Lixiviation — Extraction — Crystallization — Calcination — Furnaces — Kilns — Evaporators — Kettles — Refrigeration.

Water, Its Uses and Purification Chapter II 30

Natural waters — Boiler waters — Scale formation — Incrustation — Corrosion — Foaming — Purification of water — Numerical standards — Classification — Potable waters — Sand nitration — Boiler compounds.

Fuels Chapter III 49

Wood — Peat — Lignite — Bituminous coal — Briquettes — Anthracite — Charcoal — Water gas — Coal gas — Oil gas — Natural gas.

Sulphuric Acid Chapter IV 65

Occurrence — Raw materials — Outline of process — Glover tower — Gay-Lussac tower — Sulphur burning — Furnaces — Pyrites — Burners — Dust prevention— Chamber system — Kestner lifts — Acid eggs — Platinum stills — Contact process — Silica stills.

Nitric Acid Chapter V 91

Occurrence — Properties — Manufacturing processes.

Elements and Inorganic Compounds Chapter VI 106

A short description of over 300 elements and compounds with a brief account of their commercial application.

Ceramic Materials and Products Chapter VII 177

Lime — Kilns — Mortar — Cement — Limestone — Marl — Clays — Plaster of Paris — Kaolin — Bricks — Tile — Pottery — Stoneware — Porcelain — Glass.

v vi CONTENTS

PAGE

Pigments Chapter VIII 203

White Lead — Sublimed white lead — Zinc oxide — Lithopone — Barytes — Whiting — Asbestine — Gypsum — Red pigments — Blue pigments — Yellow pigments — Black pigments — Lakes.

Fertilizers Chapter IX 219

Raw materials — Blood — Tankage — Guano — Cyanamide — Fish scrap — Phosphate rock — Thomas slag — Belgian slag — Bone — Potash.

Illuminating Gas Chapter X 231

Coal gas — Retorts — Hydraulic Main — Condensers — Tar Extractors — Exhausters — Scrubbers — Purifiers — Water gas — Lowe apparatus — Williamson machine — All-oil water gas — Pintsch gas — Blau gas — Acetylene.

Coal Tar and Its Distillation Products Chapter XI 247

Coal tar — Retort gas tar — Oven gas tar — Producer gas tar — Blast furnace tar — Water gas tar — Pintsch gas tar — Creosote oil — Cresol — Benzene — Toluene — Naphthalene — Anthracene.

The Petroleum Industry Chapter XII 262

Petroleum — Origin — Constitution — Locality — Production — Distillation — Asphalt — Shale oil — Ozokerite .

The Destructive Distillation of Wood Chapter XIII 277

Preparatory treatment — Distillation — Retorts — Condensers — Rosin process — Hot water process — Extraction process — Wood alcohol — Acetone.

Oils, Fats and Waxes Chapter XIV 290

Classification — Constitution — Vegetable oils — Animal oils — Fish oils — Waxes.

Lubricating Oils Chapter XV 317

Choice of oils — Watch oils — Spindle oils — Loom oils — Engine oils — Crank case oils — Greases — Belt dressings — Reduced oils — Soluble oils.

CONTENTS vii

PAGE

Soap, Soap Powder, and Glycerine Chapter XVI 323

Classification — Boiling — Graining — Framing — Slabbing — Finishing — Boiled toilet — Milling — Plodding — Pressing — Half boiled — Soft soap — Floating- — Powders — Glycerine.

Essential Oils Chapter XVII 340

Crude distillation — Modern distillation — Steam distillation — Expressed oils — Macerating process — Enflurage process — Flower pomades — Volatile solvents — Absolutes — Chemical constitution — Oils.

Resins, Oleo-resins, Gum-resins, Gums Chapter XVIII 362

Sources— Constitution — Gums — Resins — Rubber.

Varnish Chapter XIX 370

Definition — Classes — Outfit for making varnish — Spirit varnishes — Oil varnishes — Baking varnishes — Japan driers.

Sugar Chapter XX 381

Raw materials — Cane sugar — Extraction process — Defecation process — Beet sugar — Sugar refining.

Starch, Glucose, Dextrin and Gluten Chapter XXI 395

Classification — Sources — Methods of manufacture — Drying — Alkaline starches— Grape sugar — Dextrin — British gum.

Beer, Wine and Liquor Chapter XXII 406

Malting — Brewing — Grapes — The Must — Fermentation — Distillation.

Textiles Chapter XXIII 429

Origin — Animal fibers — Vegetable fibers — Mineral fibers — Artificial fibers — Bleaching.

Dyestuffs and their Application Chapter XXIV 447

Textile coloring — Textile printing — Dyeing — Staining — Mordant colors — Acid colors — Basic colors — Natural colors — Azo-colors — Vat colors.

The Paper Industry Chapter XXV 459

Rag paper — Wood paper — Mechanical process — Soda proeess — Sulphite process.

Yin

Contents

PAGE

...Chapter XXVI 470 powders — Nitrogly-

Black powder— Nitrocellulose— Smokeless cerine— Dynamite— Fulminates.

Chapter I General Processes

GRINDING. In the manufacture of chemical products, one of the most important operations is that of grinding. Not only is it often necessary to reduce the raw material to a state of fine division before it can be used, but the finished product, in many instances, must be placed on the market in the form of a fine powder or paste. The result to be secured depends entirely upon the nature of the product or material and the purpose for which it is to be employed. Thus in many metallurgical operations it becomes necessary to crush very hard rocks or ores; while on the other hand some materials, like pigments, must be sold as a very fine powder. Therefore, we have two general divisions of grinding machines — those which are used for crushing or coarse grinding and those which are used for producing a fine powder. For those materials which appear on the market in the form of a paste, special forms of grinding machines are employed. The following are some of the types of grinding machinery:

JAW CRUSHER. 1 The simplest and least expensive form of crusher in use is that known as the jaw crusher. It is a very heavy type of machine and consists essentially of a stationary steel plate against which a corresponding steel jaw works on a cam, thus giving a rolling motion. The working parts may be regulated by means of an adjusting screw so as to give a coarse or fine product as desired. This machine is capable of crushing the hardest of materials. It finds extensive application in metallurgical operations where ores are to be crushed; in the manufacture of plaster of Paris; in crushing of pyrites for sulphuric acid

1 Sturtevant Mill Co., Boston, Mass.

manufacture and for many other purposes. On account of the strain this machine is always placed on a very solid foundation.

Fig. 1 represents a small-size jaw crusher used for laboratory work which may be either hand or power driven. Fig. 2 illus-

Fig. 1.

Fig. 2.

trates a heavy machine employed in crushing pyrites for the manufacture of sulphuric acid.

CRUSHING ROLLS. 1 This type of machine is employed quite extensively for reducing the product of the jaw crusher to a finer state of division. Fig. 3 shows a laboratory roller, while Fig. 4 'Sturtevant Mill Co., Boston. Mass.

illustrates a heavy type of machine used in metallurgical operations. The rolls may be either plain or corrugated. These machines are also employed for crushing soft materials. Fig. 5 represents a battery of rollers used in crushing sugar cane, while

Fig. 3.

Fig. 4.

Fig. 6 is a form used extensively for crushing seeds such as flaxseed in the manufacture of linseed oil.

ROTARY FINE CRUSHER. 1 For rocks of moderate hardness the rotary crushers are almost universally employed. These 1 Sturtevant Mill Co., Boston, Mass.

machines are provided with double doors that carry all of the grinding parts and swing open as easily as the doors of a safe, thus exposing every part to inspection. They are built with capacities of from 2 to 30 tons per hour. They may be regulated while running for fine or coarse work by turning the adju ting wheel. Fig. 7 represents such a mill, which finds extensive application in the grinding of cement rock.

CHASER. 1 There are many materials which, owing to their peculiar nature, cannot be crushed by means of the machines r\

Fig. 7.

Fig.

described above. Such substances as drugs, clays, and putty are handled in the chaser. It is also employed in mixing bams for use in the foundry, for mixing mortar and for mixing and grinding to a semi-dry state. The chaser is constructed with a stone or steel bed on which rotates one or two " edge runners " or " travelers." An arm provided with a scraper travels just in front of the runners, which brings the material under the heavy rollers, while the whole is set in a pan arranged with a gate for discharging. Fig. 8 shows such a machine.

1 Chas. Ross & Sons Co., Brooklyn, N. Y.

DISINTEGRATOR. 1 This type of machine, also known as pulverizing mill, is especially adapted for such materials as are of a lumpy nature, such as dry colors, soft pigments, borax, sulphur, starch, etc. ; also for mixing dry materials, such as fertilizers, for example. The construction of this machine is very simple,

Fig. 9.

as will be seen from Figs. 9 and 10. The steel cages run at a very high speed in opposite directions, thus driving the material through the steel bars by centrifugal force, and pounding it to a powder. They are strongly built, and may be easily and quickly cleaned by taking off the top half of the casing, 1 Chas. Ross & Sons Co., Brooklyn, N. Y.

GENEEAL PEOCESSES removing the bolts holding bearing frames to bed plate, then drawing frame and cages apart by tail screw, as shown in the illustration.

BUHR STONE MILL. 1 For the fine grinding of dry or wet materials this type of mill is in very common use. Fig. 11 shows an under-driven dry mill, which is open in order to give an idea of the grinding surfaces. This mill is employed for the grinding of soft materials such as flour, pigments and dry colors. Fig. 12 is the Ross improved paint and color mill ready for work. This mill is provided with a double set of stones having a watercooling arrangement to prevent excessive generation of heat in the grinding of paste colors and paints. In using these mills the material is fed in through the hopper and by centrifugal force is carried to the grinding parts of the first set of stones, from which it then passes to the second set. The degree of fineness is regulated by means of set screws on the side. For paste and paint grinding it is necessary to provide a scraper on 1 Chas. Ross & Sons Co., Brooklyn, N. Y.

the traveling stone to remove the product as it passes the grinding face.

BALL MILL. There are many types of these mills on the market which find application in various lines of industry. Among the most commonly used of these mills might be mentioned the Fuller-Lehigh pulverizer, Fig. 13, largely employed in the manufacture of cement, which consists of a horizontal ring or die against which revolve four balls. The balls are propelled by means of pushers. The die and pushers are chilled charcoal-iron castings.

The balls are of steel forgings. They revolve at a speed of about 155 R.P.M., and hence press against the die with enormous centrifugal force. The material to be ground is fed into the hopper which serves the feeder. The material discharged by the feeder falls down into the pan of the mill, situated below the die, and is drawn up from this in between the rapidly revolving balls and stationary die by means of air currents induced by fans placed in the chamber above the die. The material is pulverized by the rolling of the ft^^^^ G^lifeo balls against the die, the grinding action being similar to that of a mortar and pestle. The finely pulverized material is sucked upwards by means of the fans and out through the screens. The material passing through the screen falls down between this screen and the outer casing, and is discharged from the mill through the discharge spout, which may be placed at any one of four quarters of the mill. The feed to the mill and consequently the fineness of the product, may be controlled in two ways — either by a slide on the hopper or by means of the stepped pulley, connected to the screw conveyor by gearing. The mill is provided with two screens, one — the inner — of 1-in. mesh and made of very heavy wire to protect the outer one. The outer screen does not really screen, but merely controls the draft of air, and hence the fineness, since the greater the velocity the greater the carrying power of the air, and hence the coarser the product.

The Griffin mill is somewhat similar to the Fuller-Lehigh mill in operation. It consists of a steel die against which a roll also of steel is made to revolve, and it is between these two that the material is ground. The roll is suspended by a shaft from a spider, and actuated by a pulley and a universal joint. The fully ground material is sucked up and forced through the screens. The coarse particles fall back into the pans of the mill and are thrown up between the roll and the die by means of a plow attached to the roll. The finished product passes through the screen and travels from these to the outer casing and thence through openings in the base of the mill to screw conveyors.

PEBBLE MILLS. 1 Pebble mills grind principally by friction, the effect being produced by the sliding, tumbling and rollinginside of the mill of a great number of flint pebbles or porcelain balls which are mixed with the substance to be ground. The movement is caused by revolving the mill at a regulated speed. As pebble mills are not crushers, all material should be crushed to a certain degree of fineness before being charged into the machine. The mill shown in Fig. 14 is lined with vitrified por-

1 Abbe Engineering Co., New York City.

celain, thus presenting a grinding surface which will neither contaminate nor discolor the material being pulverized.

TUBE MILLS. The general principle of grinding employed by the tube mill is the same as in the ordinary pebble mill, the difference being that the material to be ground in the tube mill is fed in at one end and is delivered as a finished product at the other, the fineness of the product being regulated simply by the speed at which the material is fed into the machine. The slower the feeding the longer the material receives the action of the pebbles and the finer the discharged product will be. To make a coarse material the feeding is increased.

Some of the more modern forms of tube mills are provided with a " spiral feed." By means of a crescent-shaped opening located where the spiral starts, a certain quantity of the material is allowed to enter, and as the machine revolves this travels forward until it reaches the center, where it enters the grinding chamber. Thus after two or three revolutions there is a constant feed of a regular amount of material. From the grinding chamber the product passes through a perforated plate into a reverse spiral and thence is discharged from the center of the machine. In this way all labor of shoveling pebbles is avoided.

ROLLER MILLS. 1 For the grinding of lithographic inks, colors in varnish, chocolate and many other pasty materials the

1 Chas. Ross & Sons Co., Brooklyn, N. Y.

above methods cannot be satisfactorily employed. The roller mill, Fig. 15, obviates the difficulties encountered and is largely used for the purposes mentioned. In their construction these machines usually consist of three steel rolls, which rotate at different speeds, thus passing the product to the front, where it is detached by means of a scraper, and falls onto the apron. By means of adjusting wheels the front and back rolls are under perfect control, and may be set to any degree of fineness desired.

SIFTING. In those instances where the substance being treated is ground in a dry condition, it is often necessary to separate the coarse from the fine material. This is accomplished by the use of sifting or bolting machines, there being numerous forms and styles employed for the purpose. The degree of fineness is regulated by using either wire sieves or bolting cloth. In all cases the ground material enters the reel, and as this rotates the fine powder passes through the meshes, leaving the coarse particles in the reel.

SEDIMENTATION. In order to overcome the annoyance and loss caused by flying dust, many materials are ground in water. As the resulting turbid liquid comes from the mill it is allowed to flow into the first of a series of tanks, where the coarser and heavily particles rapidly subside, leaving the finer substance in suspension. The liquid is then drawn to the second tank, where it is allowed to remain somewhat longer than in the first tank. In each of the subsequent tanks the liquid is allowed to remain for a longer period than in the one previous, thus giving various degrees of fineness to the resulting product, the coarse particles being returned to the mill for further grinding. This operation is sometimes spoken of as " levigation."

FILTRATION. By this process is meant the separation of suspended solids from a liquid, and often presents grave difficulties; especially is this so when working with large volumes. The medium employed may be paper, cloth, cotton, wool, asbestos, slag or glass-wool, unglazed earthenware, sand or other porous material.

RIBBED FILTER. For handling small amounts of material the ribbed filter is very convenient, and consists in folding an ordinary large filter in such a manner that when inserted into the funnel it will leave canals along the side. To prevent breaking of the filter the tip should be forced well into the neck of the funnel.

BAG FILTER. A very satisfactory method of filtering coarse material is to arrange four pieces of wood as shown in Fig. 16, and on the brads suspend a piece of muslin in such a manner as to form a bag. The portion passing through at first may be slightly cloudy, but as the pores fill with the precipitate the filtrate becomes clear.

Suction Filter. This form of filter is used very largely where it is desired to retain the filtrate as well as the solid matter. It consists of a box arranged so that the lower section is connected with the vacuum pump, and over the perforated bottom is placed canvas or other filtering medium.

FILTER PRESS. A very rapid and convenient method of filtration is by means of the filter press. Although they are all built on the same principle, their details of construction vary to a marked degree. In its simplest form, however, it consists of distance frames and plates. These plates and frames rest upon a pair of parallel bars, and are held in position by means of lugs projecting from each side. Over the surface of each plate is stretched a filtering medium, usually cloth, which is held in place by means of pegs, the whole being forced against the adjacent frame by means of a screw or hydraulic pressure. The material to be filtered is forced through the channel along the top of the press and into the distance frames. The solid material is held back by the filtering medium, gradually filling the chambers and producing a solid cake. The liquid which passes through the filter is allowed to discharge into the channels along the lower portion of the press, where it may be recovered or discarded as wished. A more recent form of filter press is the Sweetland self-dumping filter, shown in Fig. 17. The material to be filtered is forced into the filter body by gravity pressure or by means of a pump. The filter body comprises two semi-cylindrical castings of high tensile strength. As soon as the filter body is filled, the pressure rises, causing the liquid portion to pass through the filter cloth, while the solid matter is deposited on the leaf in a compact form. When the filter is full the bottom half of the body is lowered, and then by reversing the pressure the cake is easily and very quickly detached.

Centrifugal Machine. 1 This appliance is used for sepa-

1 American Tool and Machine Co., Boston, Mass.

rating liquids from solids. It is especially adapted to the drying of crystals in that it throws off the adhering mother liquor by centrifugal force. It is also employed for drying yarns, textiles, wood pulp, sugar, starch, etc. The centrifuge, therefore, is used more as a means of drying than of filtration. It consists of a cylindrical perforated basket fixed to a vertical shaft, which rotates at a very high speed (900 to 1200 revolutions per minute), Fig. 18. * By means of the centrifugal force generated the contents of the basket are driven to the outer wall, where the solid material is detained, and the liquid thrown off. In working with the machine great care must be exercised lest grave accidents occur. It is also necessary to see that the machine is carefully constructed.

DRYING. Before submitting material to the dr3 7 ing process proper it may be advantageous to remove as much of the adhering liquid as possible by draining, filtering, or centrifuging. The water that still adheres is now removed by evaporation in contact with the air at as high a temperature as compatible with the substance and economical practice. Whenever waste heat is available it should be used.

In order that drying should be uniform the substance to be dried is stirred, usually by mechanical appliances. The simplest arrangement would consist of a platform of metal or stoneware heated by flue gases and upon which the material would be spread and stirred from time to time; this is not, however, an economical process. A less wasteful method is by the use of drying chambers, built of brick, wood, or metal. The chamber may be heated from the inside, or the air passing through it may be heated. To aid in the removal of the moist air an exhaust or fan is usually employed.

Where temperatures of 100° C. or less are desired the air may be heated by passing it over steam-heated coils, or the plate on which the material is placed may have a steam-heated jacket. As the point at which the heat enters the apparatus, be it steam or flue gases, is the point of greatest heat, it is usual to provide for the conveying of the material from the further and cold end of the apparatus toward the hottest portion. For this purpose the shaft furnace can be used, provided the material is hard enough and there is no need of regulating the temperature very carefully. A large number of more or less efficient forms of dryers are manufactured, among which vacuum dryers, in which the drying is done at a considerable saving of labor, fuel and time, are the most important. Vacuum dryers may be divided into shelf dryers, Fig. 19, for material that does not need to be stirred while drying; rotary dryers for material which must be continuously stirred; and drum dryers for substances like glue, which readily forms a dry film on the surface.

LlXTVIATlON. The process of lixiviation consists in the separation of water-soluble material from insoluble or less soluble material. The substance to be treated with water may be suspended in bags or baskets, or placed in tanks provided with perforated false bottoms. The solution, being denser than water, sinks to the bottom and may be removed. The material is usually submitted to a systematic treatment with water, in such a manner that the pure water first comes in contact with the nearly exhausted substance, and then with the less exhausted in another tank, and so on until it reaches the last tank containing the fresh material. Such a series of tanks is known as a battery. The term extraction is generally used when solvents other than water are employed. It is possible to extract several substances from the original raw material by the successive use of several solvents such as water, alcohol, ether, and naphtha.

CRYSTALLIZATION. Crystals are geometric solids which may form by the separation of a compound from its concentrated solution. The solubility of most substances increases as the temperature of the solvent, usually water, is raised. A limit may be reached, however, for every temperature when no more will dissolve, and the solution is said to be saturated. If the temperature be now decreased, crystals of the substance will separate; and these crystals, though formed in an impure mother liquor, may be quite pure. By evaporation or concentration of the mother liquor more crj^stals will result, which, however, will be less pure than the first crop. Thus this operation may be continued until the impurities accumulating in the liquor become so great that the crystals will enclose a large amount of foreign matter. This difficulty can be prevented to a certain extent by stirring the solution while crystallization takes place; this causes the separation of very small crystals, or crystal meal, which can then be washed so as to remove the adherent impurities. This process is usually spoken of as " Granulation."

Fractional Crystallization. Crystals may be further purified by several successive recrystallizations. This is a method used for the separation of substances when mixed in a solution; isomorphous substances, that is, those crystallizing in the same system cannot, however, be separated in this manner. The only way to proceed in such a case is to so react upon the solution as to change the chemical composition of one of the substances in such a manner that separation by crystallization becomes possible. As an instance of this may be mentioned the preparation of pure copper sulphate from a mixed solution of copper and ferrous sulphates. When blue vitriol is made from copper pyrites it is usually accompanied by more or less green vitriol. From this mixed solution only crystals of copper sulphate mixed with iron sulphate can be obtained, these salts being isomorphous. By oxidizing the ferrous to the ferric sulphate this may be avoided and pure copper sulphate prepared.

CALCINATION. In the process of calcination substances are submitted to the action of high heat, but not, however, to the point of fusion. Material may be calcined: to drive off moisture, to drive off some volatile constituent or cause a chemical action such as oxidation or reduction. The terms roasting, firing, glowing, or burning are sometimes used in place of calcination. The process is usually carried on in furnaces, of which there are three common types — reverberatory, muffle, and kiln.

REVERBERATORY FURNACE. In the reverberatory or open roaster the material to be heated is exposed to the direct action of the fire gases. It consists essentially of an arched chamber built of brick and heated from a grate placed at one end, while the products of combustion and reaction are removed by a chimney at the other end. The material is placed upon the bed of the furnace, the fire gases pass over it and are deflected by the arched form of the roof of the furnace so as to come more directly in contact with the charge. The insides of such furnaces are lined with firebricks, while the outsides are built of common bricks.

If an oxidizing reaction is desired, that is, if the fire gases are to contain an excess of oxygen, such condition may be produced by setting the fire bars widely apart and feeding the fuel in thin layers at a time. Should a reducing action be desired, the fire bars must be placed closer together and the fuel charged in thick layers.

MUFFLE FURNACE. The muffle furnace, closed or blind roaster is built in such a manner that the fire gases do not come in contact with the substances to be calcined. It generally consists of a muffle of firebrick with the flues so arranged that the hot gases pass underneath the bed of the muffle and are then conducted over the top, back to some point near the grate, where they are discharged into the chimney. A pipe is sometimes fitted to the top of the muffle in order to discharge any gases which may be formed during calcination.