DE1103900B - Process for the production of uniform granulates from meltable materials - Google Patents

Description

Process for the production of uniform granules from fusible Substances During the manufacturing process of mineral substances such as fertilizer salts etc., part of the material falls in a grainy manner, but another part more or less fine-grained or dusty.

The consumer desires the finished product depending on the intended use dust-free or in a well-scattered condition.

It is already known that mineral substances only melt when they melt brought into a liquid and then by cooling into a solid granular state can be (German patents 658952 and 663 089). With these well-known However, the process is the heat requirement and thus the cost of the graining process so high that their application, taking into account the relatively low Revenue prices for the mass products are not economically viable.

In the case of the procedure which is the subject of the application, d The graining process with that which is necessary in any case in the rabmen of the driving gear Organically coupled drying process.

The main features are: 1. that only the fine portion of the dried in a fuel gas-heated, cocurrent-operated drying drum Good is screened off and melted, 2. that the process of melting the pain portion accumulating waste heat is used in its entirety for the drying process.

Due to these two measures, the total heat consumption of the combined Drying and graining process only by the amount of radiation losses Granulation systems that can be kept to a low level by insulation, over the heat consumption already expended for the drying operation, d. H. the grainy or dust-free nature of the entire product becomes practical achieved with only a very small additional expenditure of heat.

In contrast to this, according to the method of the German patent specification 658 952 first dried the entire amount and then d in a rotary kiln melted. So it will not only be that which is already present in the dried material granular portion, which already meets the market requirements, unnecessarily melted, but it is also advantageous thermo-technical to the invention There is no coupling of two processes taking place at different temperature levels.

Apart from the higher investment costs for the corresponding larger granulation system, the heat input for the melting process is many times as high of the one that is required at the registration fee.

Also for the working method described in the German patent specification 663 089, according to which the entire exhaust gases from the rotary drum melting furnace connected behind the drying drum together with the drum exhaust into the chimney leading into the open air that is true.

Only the small amount of heat that is used to cool the melted material The cooling air used is obtained from the sensible heat of the schnitzel fed back to the drying process in the form of combustion air.

Sieving the fine material from the product of a melting process is known per se from German patent specification 643 410. The sifted fine material However, there it is fed back into the melting process itself.

This procedure is cumbersome and expensive.

In the case of the registered process, however, the centrifuges are used or the other dewatering devices incoming moist material in a normal simple Drying drum dried, the fine material then connected behind the dryer with the dedusting of the flue gases separated by sifting or sieving and only this fine fraction (about 20 to 30%) is granulated in the melting process. Since both the Exhaust heat from this melting process as well as the sensible heat of the melted one Good things with the exception of the low radiation losses from the apparatus back into the drying drum returned and used there to dry the moist material becomes a granular one Total property obtained with practically no additional heat and energy input.

The subject of the application is not exhausted by the fact that the undersize is separated from a dry material of fusible substances and in a Melting stage is granulated, rather these two processes are completely independent of one another thermally linked, in a very specific way and only through this the proven surprising progress achieved.

A simultaneous drying and. Granulation is an example known from German patent specification 586 506. This contrasts with the subject of the registration due to the direct current flow of dry material and heating gases through the mechanical Abrasion within the drying drum and by the blasting effects of the moist material trapped, evaporated by the temperature increase with expansion effect Water an increase in the fine fraction.

When using direct current occurs through the touch of the coldest Moist material with the hottest fire gases as soon as it hits the drum a sudden removal of moisture, so that incrustations do not occur. Because these conditions exist, they must be those that occur in direct current operation relatively high exhaust gas temperatures and the associated heat losses be accepted.

Embodiment The moist material arriving from the production is with a conveyor (Sclmecke od. Ä.) 1 into the incidence chute of the drying drum 2 transported.

Here it comes with the from the dry furnace 3 or from the melting and granulation system 4 come into contact with incoming fire gases. The goods to be dried and the fire gases flow through the drum in the same direction. This operating mode is required to avoid incrustations at the beginning of the drum.

The dried material falls through the dropout housing at the end of the drum into a sieve device 5, which oversizes the entire dried material in finished product and fine material separates. The entire fine material or just part of it is transported via a conveyor system6 conveyed into a pocket above the granulation system 4.

From here it is finely distributed with a distribution apparatus 8 introduced into an oil- or gas-heated smelting and granulation plant 4.

The molten material falling out of the melting and granulation system 4 It can be introduced directly into the feeder screw 1 either in liquid form or in the form of drops and mixed there with the moist material.

But it can also use the connection 9 with the ali-sieved fine material brought into contact for sintering 10 and again a two-stage classifier system 11 are supplied.

The fine fraction from this sieving process is via the connection 12 returned to the pocket 7. The middle product leaves together with the finished product duct the process. The oversized grain can be removed from the screening plant together with the oversized grain 5 can either be fed back into the drying drum 2 or a crushing plant. The exhaust gases exiting from the smelter 4 are passed through the channel 13 into the Dry drum furnace 3 introduced.

If the exhaust gases from the melting plant are insufficient for drying, so the missing amount of fire gas is supplemented by the dry drum furnace, which is operated with solid, liquid and gaseous fuels.

PATENT CLAIMS: 1. Process for the production of uniform granules from fusible substances or mixtures of substances in anhydrous form by application a drying process for the moist starting material in connection with a melting process, characterized in that only that behind the flue gas heated drying drum separated fine material fed to the melting process and the entire waste heat from the melting stage is used for the drying process.

Claims (1)

2. The method according to claim 1, characterized in that the molten Well introduced in a manner known per se into the untrocled material and with it is mixed. 3. The method according to claim 1, characterized in that the separated Fine material sintered with the melted material, the mixture obtained in this way again Subjected to the separation process and the resulting fine material fed to the melting process will. Considered publications: German Patent Specifications No. 586 506, 663 410, 838 596; French patent specification No. 1,060,698, British patent specification No. 654 272, Henglein: Grundriß der Chem. Technik, 1949, p. 346, paragraph 4. from below.