DD270699A1 - METHOD OF MANUFACTURING HIGH-QUALITY MGO PRODUCTS WITH VERY LIMITED RESTRICTING CHANNELS AND DIFFERENT FEELNESS - Google Patents

Abstract

The invention relates to a method for producing high-value MgO value products with very limited Koernungsbaendern and different fineness, which can be used in the refractory industry, the ceramic industry, the electrical industry, in Fuellstoff- and pigment production and as a chemical and pharmaceuticals. The starting materials used are final, intermediate or waste products of sintered MgO plants, which are ground in a sieve drum mill with a low-wear inner lining and high-chromium alloy castings. According to the invention, the object is achieved by using monodisperse ball fillings with ball diameters between 30 and 80 mm in the sieve drum mill and producing a mill discharge stock with at least one transfer gap, which is subsequently divided by a classifying cut in the area of a transfer gap into two or three pass lines more MgO value products are separated with a uniformity coefficient of RRBS distribution of n1.5.

Description

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Field of application of the invention

The invention relates to a process for the preparation of high-quality MgO value products with very narrow grain size bands and different fineness, which in the refractory. Oustiie, the ceramic industry, the electrical industry, in the filler and pigment production and can be used as a chemical and pharmaceuticals ,

Characteristic of the known state of the art The production processes for producing MgO from MgCl ₂ leaches are the subject of a large number of Invention descriptions, e.g. DD 46225, DD 51239, DD 88788. DD 218758, DD 220951, DD 234261, and are incorporated simultaneously in

the literature described in detail, for. B. Ulimann Encyclopedia of Industrial Chemistry, Volume 6, Verlag Chemie

Weinheim, Germany. The basic principle of the plant which has been in operation in the GDR for several years is based on the process patent AT 340365

and AT 356630. Details are the company publication no. 3 + 5 of the company Andritz-Ruthner Industrieanlagen AG, Vienna and

Sprechsaal 120 (1987) 12, pp. 1115-1118. Starting from a concentrated, purified MgCl ₂ -Edelsolsole occurs at 1000K in the pyrolysis reactor, the formation of MgO Spray oxide, which, after extensive wet cleaning in the multi-deck oven at 1200K, becomes finely dispersed MgO-Kauster

is converted.

After briquetting into almond-shaped green briquettes, the generation of a high-purity one takes place in the shaft furnace at 2200K MgO 'sinters with air.em Kornraumgewicht of> 3.40g / cm ³ . As salable value products of the MgO splitting plant are the

consider reactive MgO-Causter and densely sintered MgO sinter.

In the manufac turing process, the combustion gas to be discharged or the cooling air are also used at several points

discharged considerable amounts of solid and deposited in cyclones.

Due to the heterogeneous properties, in particular with regard to the degree of firing, the grain distribution and the Amount accumulation, these MgO dusts represent technologically unused waste products. The previously practiced,

Uncontrolled Zumiichung these MgO dusts to intermediates or end products is from the above and others

Reasons (eg increased wear of the briquetting rollers, undesirable undersize in the MgO sinter, dusts are with Defective impurities such as B ₂ O ₃ enriched) in any case refuse. So far, unsatisfactory partial solutions for the utilization of valuable chemically pure MgO dusts are: According to DE 2255517 a magnetic fly ash with chrome ore is processed to chromium magnesite stone. Especially the ,

insufficient total amount of MgO dusts is ontgegen this use variant.

According to DD 226133 MgO dust is proposed after a fractionation as investment or for Fouer / asterzeugnisse. The disadvantage is that only subsets can be used and the fact of a process-related contamination enrichment

including moisture absorption is given no importance. In addition, the procedural

Solution completely left open. In the case of DD 234261, a combination of milling and fractionation for MgO is used. Stäubo and MgO sinter for the above applications, without the procedural approach and the

thereby to be solved difficulties also only suggestively white dsn.

Taking into account the concrete property relationships, products from Spalt-MgO sintering plants are used within the scope of

mechanical process stages converted into corresponding value products.

For such manufactured MgC products is the use in the refractory industry, ceramics, electrical industry, and filler Pigmentharstellung and known as a chemical and pharmaceuticals. As mechanical Verfahrensctufen known crushing and Klassieraggregate are generally used. With regard to machine-technical details, reference can be made to standard works (eg K. Höffl, Zerkleinarungs-und Classifying machines, VEB German publishing house for primary industry, Leipzig 1985). In DD 154096 and DD 154C97 methods are described where MgO-Produkta in spring roller mills followed by Air classification or be produced in DD 137090 in eiiwr striking pin mill with downstream vibrating screen. Either Fedorrüllenmühlen unc! eret quite Schlagstiftmühlen are very wear-intensive crushing units, which are in the

technical scale for reasons of wear durchge-set only for comminution of soft or medium-hard materials.

In contrast, MgO sinter as a hard and very abrasive substance causes a hv ^h '<ri in these comminution aggregates

Metallic abrasion and leads to strong chemical contaminants.

In addition to the chemical purity, the abuse properties of finely dispersed MgO powders for the b 'are known Use cases determined by the particle size distribution. For the analytical representation of the particle size distribution of The RoEUi-IIPmmler-Sperling-Bennet distribution (E. Rammler, A. Bahr: Grain size distributions Chem. Techn. 24 [1972] 6, pp 345-351 and 12, pp 738-743) proven. By the parameters d 'and η is

this distribution clearly described, where both parameters are not independent of each other. While the parameter d 'describes, with limitations, the fineness of the grain collective *, the parameter η, as an increase in the RRSB straight, characterizes the grain bandwidth and is referred to as the uniformity coefficient.

The required utility characteristics of finely dispersed MgO powders in the form of high packing density and Flowability u. v. a. m. sometimes cause very narrow granulation bands with different parameters d 'of the RRSB distribution. So z. As a common enamel MgO, which is used as investment material for heating conductors in the electrical industry

finds parameters of the RRSB distribution of d '= 220μη. and η = 2.5.

Crushing products generally have coefficients of uniformity η of 0.8 to 1.2 and can be replaced by a

Increase downstream one-stage classification by air classification or sieve classification in the parameter η only insignificantly, that is narrow in the granulation band.

The Kornbandforderung partially asked to finely dispersed MgO powder (n from 1.5 to 2.5) are a! S extreme to call and

are also not met with the proposed solution in DD 253605 dor grinding in a Siebtrommelmühle (n of 1.0 to 1.4). So far, this fact was hardly considered in all known solutions.

Starting from the state of the art, grain sizes with η between 1.5 and 2.5 can only be obtained by narrow fractionation

from crushing products into many grain fractions and then mixing certain grain classes as described in DD 234261. Such a procedure is very expensive, requires high product costs and allows only one

Partial use of the shredded product. Object of the invention

The aim of the invention is to develop an effective process for the preparation of high-value MgO value products with very narrow grain bands and different fineness, which allows use of the final, intermediate or waste products of sintered MgO plants.

Explanation of the essence of the invention

The invention has for its object to develop a process for the preparation of high-value MgO value products with very narrow grain straps and different fineness, are used as the starting final, intermediate or waste products of sintered MgO plants and this in Siebtrommelmühlen with low-wear inner lining and Hochchromlegierten Gußmahlkugeln is ground.

According to the invention this object is achieved in that in the screen drum monodisperse Ku jelfüllung6n be used with ball diameters between 30 and 80mm and a Mühlenaustragsgut is generated with at least one gritting gap, which then by a Klassierschnitt in the range of a grain gap in two or more MgO value products with uniformity coefficients the RRBS distribution is separated by η> 1.5. It is essential to the invention that the monodisperse ball fillings in the sieve drum during grinding of the MgO sintered final product are 60 to 80 mm, preferably 70 nm, and in the grinding of intermediate or waste products in the form of MgO sinter dust or MgO cyclone dust 30 to 50 mm, preferably 40 mm. is.

Furthermore, it is characteristic that the classification of the Mühlenaustragsgutes the Siebtrommelmühle in the area einor Körnungslücke down to a Tr6nnkorngröße of 630μητι with a Mehrdecksiebmaschiene succc wherein the upper screen deck for Schutzsiebung for the oversize is covered with the same mesh size as the Siebtrommelmühle and the lower screen deck the lower screening decks are equipped with the mesh size or the mesh sizes for the respective required separation size bzv /. , and that for the classification dec mill discharge good »the Siebtrommelmühle in the range of a Körnungslücke with required Trennkorngröße · η> 630 μτι a regulatable Streuwindsichter is used, wherein on the Sichtraumfläche related specific Sici) terdurchsatzm _A ^# <1.0t / hm ² ,

According to the invention, the production of finely dispersed MgO powders having different reactivity and very limited fineness of grains with η> 1.5 can be achieved by the production of unusual grain distribution particles in the comminution product of the sieve drum mill under described pouring conditions and a subsequent separating shear classifying cut. In order to obtain the required very steep granulation bands in the classification product, it is essential that the class fraction be produced with very good selectivity in the region of a sparse grain fraction or a grain gap.

Exemplary embodiments The invention will be explained in more detail with reference to two exemplary embodiments. example 1

A partial flow of the final product of a sintered MgO plant, the MgO sinter with particle sizes of> 15 mm, is ground in a sieve drum mill with a low-wear inner lining and high-chromium alloy cast balls. The ball diameter of the introduced monodisperse ball filling is 70mm. The sieve drum mill is equipped with a sieve lining with 500 μm mesh size, has a grinding chamber diameter of 630 mm for a throughput of about 50 kg / h and is filled with a ball mass of 100 kg. Under these boundary conditions, the following grain distribution results for the mill discharge material of the sieve drum mill:

grain fraction fraction mass distribution density proportion of μνη % % / Μιτι > 500 3.5 0.03 500-400 9.5 0.10 400-315 11.0 0.13 315-250 13.0 0.20 250-200 7.5 0.15 200-160 4.0 0.10 160-125 9.5 0.27 125-90 6.5 0.19 90-63 3.0 0.11 63-40 9.0 0.39 <40 23.5 0.59

The graphical representation of the distribution density F ₃ (d) of the Mühlenaustragsgutes on the grain size in Fig. 1 shows that in the Kornfraktionen 90-63pm and 20Ο-160μπι "grain gaps" or sparse Komfraktionen occur. The mill discharge material of the sieve drum mill becomes adjustable for classification in the area of a grain gap Fed to squaring machine. At a throughput of up to 100kg / h, a class USR400 classifier with a Sichtraumdurchmessor of 400mm used (m _A · = 1t / hm ² ) The following classifier data is selected: Internal fan speed: 1400rpm Spreading plate speed: 800rpm In the grain structure of the mill discharge material of the screen drum mill, the classifier thereby achieves a separation cc; r.size of The separation products of the classifier have the following grain composition:

grain size oversize 2 fines in pm Backlog in% 30 500 46 0 315 76 0.5 250 PG 1.0 125 93 1.5 90 98 2.0 63 6.0 40 30.0

The parameters of the RRSB distribution of the classifier separation projects are:

η d'inpm

Grobgut 1.75 200

Fines', 6 35

With this classification in the classifier, about 70% of the feed material mass flow is produced as coarse material. Example 2

"he MgO cyclone dust separated from the exhaust gas of the sintering furnace of a sintered MgO plant by cyclones, which is chemically pure with MgO contents between 98.5% and 99.9%, has a grain size range of 10r..m to 0mm, different degrees of firing and at 8 ₂ O _r contents> 0.02%, a product which can not be used for MgO sintering is ground in a sieve drum mill with a grinding chamber diameter of 630 mm and equipped with a sieve lining of 31 * ϊμη> mesh size a ball diameter of <0rr "n aui, and the introduced ball mass is 80kg.With a throughput of 60kg / h, the mill discharge of the SieNrimmelmühle has the following grain distribution:

grain fraction Fraction mass fraction in pm in% > 31ö 1.0 315-250 10.0 250-200 13.0 200-160 12.5 160-125 13.0 125-90 9.0 90-63 6.5 63-40 13.5 <40 21.5

The Mühlenaustragsgut has a "Körnungslürke" in the fraction of 125pm to 63pm.

To classify the mill discharge material in the area of the grain gap, a multi-deck sieve machine M / 018 with sieve cover dimensions 1.5m χ 0.5m is used. Three screen decks with 315pm, 100μηι and 63pm mesh size are used. The upper sieve deck, covered with a mesh size of 315pm, is used for protective screening against oversize grain. The second screen deck is only used throughput relief of the third separation surface. The separation products of Mehrdecksiebmaschine have the following Kornzussrnrnensetzung:

grain size oversize 0 Fe in pm Backlog in% 16 315 76 0 250 92 0 125 96 5 90 98 15 63 30 40 58

The parameters of the RRSB distribution of the separation products are:

Coarse material η = 2.60; d '= 200prr

 Fine material η = 1.65; d '= 60 pm

From the feed material of Mahldecksiebmaschine fall about 55% as coarse material. In the same way, the separated from the cooling air of the sintering furnace by means of cyclones MgO sintered dust is processed. The MgO sinter dust, which with MgO contents> 99% is very pure chemically, of the degree of combustion homogeneous, d. H. final sintered, is and in

In the hitherto conventional technological procedure, the MgO sintered dust is added to the MgO sinter, although it has the

Grain claims on the final product do not correspond and thus this deteriorates in quality. The invention has compared to the »state of the art follow each lead:

- Use of waste products from the MgO sintering plants

- Effective processing of the final product MgO sinter to the highest value product

- - production of high quality homogeneous products with a narrow range of grain size

- Optimization of production properties.

Claims (4)

claims: 1. A process for the preparation of high-value MgO value products with very narrow grain bands and different fineness of final, intermediate or by-products of sintering MgO plants by grinding h a screening drum mill with a low-wear inner lining and high-chrome-ground Gußmahlkugel, characterized in that mor .odisperso ball fillings with ball diameters between 30 mm and 80 mm in the sieve drum mill and a Mühlenausagagsgut is generated with at least one grain gap, which then by a classification cut in the range of a grain gap in two or more MgO value products with uniformity coefficients of the RRSB distribution of η> 1 , 5 is separated. 2. The method according to claim 1, characterized in that the ball diameter of the monodisperse ball filling m of the screen drum mill in the grinding of the final product of the sintered Mg O briquettes 60 mm to 80 mm, preferably 70 mm, and the grinding of intermediate or waste product in the form of MgO sinter dust or MgO cyclone dust is 30mm to 50mm, preferably 40mm. 3. The method according to claim 1 and 2, characterized in that the classification of the Mühlenaustragsgutes the screen drum mill in the range of a Körnungslücke down to a separation grain size of 63pm with a Mehrdecksiebmaschine, the upper Siebdeckzur protective screening for the oversize with the same mesh size as the Siebtrommelmühle is covered and the lower screen deck or the Moschenweiten for each required separation grain size is or are equipped. 4. The method according to claim 1 and 2, characterized in that for the classification of the Mühlenaustragsgutes the Siebtrommelmühle in the range of Körnunpsiücko at erforder'ichen separation grain sizes <63 / im a controllable Streuwindsichter is used, wherein the related to the Sichtraumfläche specific visual throughput m _A * <1, Ct / hm ² is.