CHAPTER XVI.FERTILIZER.

Fertilizer — Blood — Receiving Tank — Cooking — Pressing — Purity — Storing — Quick Handling — Tankage — Quotations and Value — Grease — Influence of Stick — Digester Tankage — Slime — Dryers — Drying — Expense for Drying — Commercial Fertilizer — State Regulations — Mixing Materials — Conversion Factors.

—In this department we discuss the manipulation of the products after leaving the tanking process in the case of tankage, and of blood, beginning with its release from the animal.

—The sources of the collection of blood are from animals slaughtered, viz: cattle, sheep, calves and pigs. In nearly every instance this is collected at a given point near the sticking rails and transferred to the fertilizer department for processing.

It is rather difficult to pump blood, although it can be readily done with a ball valve pump, or a centrifugal pump. The latter is satisfactory if foreign substances can be kept out, and if the reservoir can be situated high enough so that the blood can gravitate to the suction of the pump. Mechanical agitation is a benefit in the receivers. A very satisfactory way to handle blood is by means of a blow tank. This is a tight, heavily constructed cylinder with an admittance valve on the inlet pipe, and a closing valve on the discharge pipe; the latter preferably a quick opening valve. A means for admitting air or steam to the blood is arranged. To operate, the valve on the inlet line as well as the outlet valve is closed, and air or steam pressure is built up as required for the lift. The outlet valve is then quickly opened when the contents of the tank is virtually “shot” to the receiving tanks.

—This is preferably a closed type of tank with an air vent to allow displacement of air when blowing blood. It is preferably situated above the cook tank with an admittance valve between them so that blood can be lowered to the cooking tank at will.

—Blood should be “baked,” not boiled. By this is meant, the steam should be admitted slowly and the heat dispersed through the mass rather than boiled violently, by admitting high pressure steam. The blood, by this method, seems to coagulate in larger grains, and, in pressing, a larger proportion is retained in the cloths, while the serum or white water draining away is of a lighter color, with the net result that the yield of blood is better.

—The pressing is performed in the same manner as described for tankage, except that the material is handled dry. The waters from cooking, as well as from pressing, are saved for evaporation as tank water. Blood when pressed properly is “caked.” It should be broken up before being passed to the dryers.

—Means should be provided and arrangements made to keep all raw or fluid blood free from water and manure. Frequently cattle that are hay or grass fed, have a draining from the stomach via the mouth when hung, and comparatively large quantities of undigested food are spilled. This should be collected before the animal is stuck and prevented from mixing with the blood.

—After drying, blood should be cooled and stored in piles on the floor in dry rooms to be put in bags at the time of shipment. It is usually unnecessary to grind or screen it. It should be dried to 8% moisture.

—Blood is so highly susceptible to decay that it should be handled quickly and with as little contact with air as possible.

—This name embodies the dried material from the residue in the tanks after cooking in digesters, and pressing. It is classified into several grades. Digester tankage, is usually sold for stock foods. No. 1 tankage of commerce, has a high nitrogen content and low percentage of bone, it isusually produced from beef tanks; No. 2 tankage is low in nitrogen or ammonia, as it is known to the lay-mind, and high in bone. The usual comparative analysis is:

—Tankage and blood is usually sold on its value per unit of ammonia. That is to say, if blood be quoted at $3.00 per unit of ammonia and analyzes sixteen per cent, it sells for $48.00 per ton. Tankage may contain eleven per cent ammonia and twelve per cent bone phosphate, quoted at $2.75 per unit, and 10c per unit respectively, which would make the relative market $31.45 per ton.

By reference to market quotations it will be noted usually that the lower the ammonia content, the lower the price per unit of ammonia, consequently it behooves the maker to produce all the No. 1 tankage possible, and this is accomplished by cooking bone as raw bone and separately—in preference to tanking it.

—Grease in fertilizers or dried tankage is a positive detriment. It is useless and valueless, consequently the point to be striven for is to lower the percentage of grease to the minimum. The best methods known are described under tanking. Some packers doing business on a large scale have “degreasing” plants where the grease is extracted by naphtha process, but, this is a highly specialized department and not desirable in a small plant. By careful attention the grease can be lowered to eight per cent on dry basis analysis.

—The use of stick in tankage drying adds greatly to the average ammonia content. Dried stick separately analyzed yields 15¹⁄₂ per cent ammonia, greatly increasing the value of the product in which it is used.

—This is a general name for the product sold to pig feeders for providing a nitrogenous element in their feeding. State Agricultural Departments and packers have been conducting campaigns for years introducing this as a feed. It is usually a No. 1 tankage made from freshly killed material and promptly dried. It is supposed to contain a stated protein content, which is really a multiple or unitbased upon its nitrogen content, 5.137 being the factor. Stick is used in the digester tankage and with benefit provided it is kept sweet.

In hog producing localities practically the entire output of tankage can be disposed of to the farmer for stock food purposes.

—The slime scraped from intestines in the casing department has a high ammonia value and should be collected and cooked in a manner similar to the method used in cooking blood.

—This operation consists of extracting the moisture from the tankage by means of air which is used as a vehicle to carry away the moisture. Various devices are employed for performing this function, such as barometric condensers, siphon tees, pipe condensers, and fan with air wash tower. There is some objection to all of these types, and each operator usually has some home-made device based upon experience. The fan is the more logical; it sweeps a large volume of air through the dryer by withdrawing it and passing it to the wash tower. The air carries away the moisture. To dry cheaply have a positive circulation of air through the dryer by keeping the inlet open, the fan attached to the air outlet connection. Single or multiple of dryers can be arranged on one fan.

—The principal apparatus in the fertilizer department is the dryer. Of these there are several types.

—In direct fire dryers, the tankage and flame produced by the use of oil, coke or coal, are introduced and passed through a cylindrical rotating machine similar to a cement dryer. The dried tankage is discharged at the opposite end from the feed, and the gases and moisture pass through a water spray and chimney to the air. It is practically impossible to operate a dryer of this type without producing an offensive odor in the surrounding territory and they are also considered hazardous from a fire standpoint.

—This type of dryer is shown in the illustration (Fig. 75) and is of the steam jacketed type. The barrel is stationary with a revolving shaft and extended arms carrying the tankage upward which falls back through the air.

—This dryer is also illustrated,Fig. 76, and is of the same type, except that the shaft is placed vertical and the revolving arms at right angle to the shaft device which accomplishes the same result.

FIG. 75.—ILLUSTRATING THE SMITH TYPE OF DRYER.

FIG. 76.—SHOWING THE ORD TYPE OF DRYER.

—In a charge type of machine where batches are placed in the machine and unit lots dried, the expense for drying seems to be per short ton, about as follows: Labor, $1.25 to $2.00; Dryer repairs, $0.75 to $1.25; Steam, variable. The item of steam is quite a large factor. In a well handled equipment, properly insulated, about ³⁄₄ of a pound of moisture can be extracted per pound of steam condensed in the jacket, when drying tankage, and ⁶⁄₁₀ of a pound when drying blood. The latter requires about twice as long to dry as tankage; in other words, the output per hour of dryer operation is about one-half.

—Commercial Fertilizer is the name generally applied to prepared or diluted mixtures thought to be best adapted for use on ground or for some special crop. The standard tankage as produced contains an ammonia content of from eight to twelve per cent and may be short in other ingredients such as potash and acid phosphate, which are mineral substances, usually converted to a form readily soluble, or in condition to be assimilated. Also the ammonia content is reduced to a moderation, the dilution being accomplished by the use of a filler, such as pulverized dried peaty soil, which has the advantage of carrying a certain quantity of humus or selected sand which serves a drill nicely.

—Most states have found it desirable to protect the purchaser by insisting that an analysis of the fertilizer be supplied with each shipment, indicating the content, the state then making sporadic analyses to see that it generally qualifies to the stated contents.

—The mixing materials used are:

Dried Tankage.

Dried Blood.

Bone Meal.

Steam Bone.

Acid phosphates, which is phosphate rock treated with sulphuric acid—a more or less complicated process—and which product is usually purchased by small works.

Muriate of potash, a substance known as kainit usually produced from mines in Germany, although some potash is being produced from sea weed in America.

—The following table will be found handy for changing the bone quantity into another term, as for example, wishing to know the per cent of nitrogen if ammonia be expressed:

CONVERSION FACTORS

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