DE3324083C1 - Process for minimising the disintegration on reduction of iron ore agglomerates as blast furnace charge - Google Patents

Abstract

A teaching for a technical solution is provided and supported by experimental results, and it is proved that the disintegration on reduction of iron ore agglomerates can be eliminated or diminished if, before the agglomerates are prepared, reagents containing halogens or compounds thereof are added to the starting materials. As a result, an improvement in the disintegration values can take place immediately or even in the course of the storage period, albeit for a limited time. A disintegration on reduction occurring after prolonged storage is far less pronounced for agglomerates prepared with halogen-containing reagents than for untreated agglomerates.

Description

The object of the invention has been made according to the conditions of the following Examples checked.

Example 1 The influence of the addition of NaCl-containing substances is shown Reagent for the starting concentrate on the reduction disintegration of burned iron ore pellets, especially on their strength behavior after aging for several weeks according to the following tables 1 and 2.

Table 1 Chemical analyzes of iron ore pellets without addition of reagent and after adding 0.17% by weight of sodium chloride (NaCl) chemical composition without addition of reagent after treatment (in% by weight) with 0.17% by weight NaCl Fe 65.7 65.7 FeO 0.5 0.5 SiO2 4.70 4.70 Al2O3 0.26 0.26 CaO 0.33 0.33 MgO 0.07 0.07 Na2O sat. 0.04 0.133 Na2O soluble in water <0.001 0.005 K2O total 0.020 0.020 Cl- tot. <0.005 0.005 From the analyzes it can be seen that water-soluble Na + is also present in the treated iron ore pellets is practically no longer available, likewise hardly any Cl-. Against it has the Na 2 O content after the treatment in the pellets compared to the untreated pellets increased by 0.09% from 0.04% to 0.133%. It thus has a transformation during pellet hardening of the Na + of the table salt took place in Na2O, while the Cl- as largely more volatile Is part of the treatment process.

Table 2 Results of the disintegration tests Reduction disintegration type of Treatment without treatment with 0.17% NaCl treatment Type of storage not stored Pellets not stored pellets stored pellets stored 4 weeks 8 weeks pellets 4 weeks 8 weeks Reduction strength% by weight + 6.3 mm 85 78 37 79 88 76% by weight + 3.15 mm 93 89 90 93 96 90 Reduction abrasion wt; O / o - 0.5 mm 6 8 6 4 3 6 Table 2 it can be seen that the unstored pellets with and without the addition of sodium chloride have roughly similar decay values. On the other hand, the strength falls after one Storage of the pellets not treated with saline for four weeks, and the The proportion of abrasion increases. The pellets show an even greater loss of strength 8 weeks storage time. Surprisingly, for those made with table salt Pellets achieved improved strength after storage for four weeks as well also reductions in abrasion. After 8 weeks of storage they deteriorate the values, but the strength level is then still roughly in the range of Baseline values. The addition of table salt thus becomes the same as that observed for many types of pellets rapid deterioration of the decay data during storage not only prevented, rather, their disintegration properties are compared to the fresh ones that have not been stored Pellets sustainably improved. Some loss of strength occurs, however even with these pellets after a further storage period, but far less than for untreated pellets.

Example 2 From our own experiments and the literature it is known that by adding small amounts of CaC12 to iron ore sinter mixes a reduction the alkali content can be achieved through their volatilization during manufacture can. It has now been checked whether the grain disintegration also occurs when reduction begins the addition of CaCl2 can be positively influenced. The determined results of the Investigations on 2 types of sinter made from different raw materials and with different Basicity established are summarized in Tables 3 and 4.

Table 3 Chemical analyzes of the iron ore sinter analysis grade sinter A Sinter B Type of treatment without 1% CaCl2 addition without 1% CaC12 addition CaCl2 addition for sinter mix. CaCl2 addition to the sinter mix.

Fe total 54.8 54.9 52.9 53.4 FeO 11.7 12.0 12.0 12.6 SiO2 6.5 6.6 8.2 8.4 Al2O3 1.5 1.5 1.6 1.6 CaO 9.8 9.9 9.9 9.6 MgO 1.3 1.3 1.3 1.3 P 0.07 0.07 0 , 07 0.08 S 0.03 0.03 0.07 0.05 Na2O 0.07 0.05 0.07 0.05 K20 0.06 0.01 0.09 0.02 Cl- <0.005 0.05 <0.005 0.05 Base degree CaO / SiO2 1.51 1.50 1.21 1.14 As the analysis values show, when CaCl2 is added, there is a clear reduction in the alkali values achieved after the sintering process, especially with K2O. The Cl - contents, however, are for the sinter types without CaCl2 addition at <0.005%, for those treated with CaCl2 at 0.05%. Obviously a certain amount of Cl has been taken up by the sinter; As the analysis values show, the predominant proportions are during sintering volatilized Table 4 Results of the disintegration tests of sinters A and B according to Table 3 Reduction disintegration Type Sinter A Sinter B Type of treatment without 10 / o CaCl2 addition without 1% CaCl2 addition CaCl2 addition to the sinter mix. CaCl2 addition to Sinter mix.

Reduction strength% by weight + 6.3 mm 15 22 21 35% by weight + 3.15 mm 40 57 48 63 Reduction output wt .-% - 0, Smm 17 12 14 8 Table 4 can be seen that for both sinter types A and B the reduction strengths, expressed in parts by weight greater than 6.3 mm or greater than 3.15 mm increase considerably if the ore mixtures occur CaCl2 is added to the sintering process, at the same time the decomposition abrasion values are reduced, expressed in parts by weight smaller than 0.5 mm by almost 50%.

We also have reviews of the other quality characteristics of the examined Pellets and types of sinter, such as mechanical strength, reducibility, standing behavior at a reduction temperature of 10500 C or swelling in the case of pellets result in these characteristics the admixtures have not changed in any way.

The results obtained from Examples 1 and 2 of this application clearly show that with the invention an improvement in the reduction data (higher Strength, less disintegration) compared to the conventional comparison iron ore agglomerates is achieved.

Claims (6)

Claims: 1. Method for minimizing the grain disintegration of in the blast furnace or lower shaft furnace when a reduction in the temperature range begins between 400 "C and 600" C used as a Möller constituent for pig iron production Iron ore agglomerates according to patent 3242 086 d a d u r c h g e k e n n n z e i n e t that the raw materials used for agglomeration production before agglomeration treated with a reagent which switches off or reduces the reduction decomposition will. 2. The method according to claim 1, characterized in that the to The reagents used are halogens and / or their compounds. 3. The method according to claims 1 and 2, characterized by a Rate of addition of reagent or reagents - based on the iron content of the used Raw materials - should be between 0.05 and 4 percent by weight. 4. Process according to Claims 1 to 3, characterized in that the reagents used for treatment are in solid form. 5. The method according to claims 1 to 3, characterized in that that the reagents used for the treatment are halogens and / or their compounds containing solutions are. 6. The method according to claims 1 to 3, characterized in that that reagents are used in the suspended state for the treatment. The invention relates to a method for minimizing grain disintegration from in the blast furnace or lower shaft furnace when a reduction in the temperature range begins between 400 "C and 600" C used as a Möller constituent for pig iron production Iron ore agglomerates according to patent 3242086. For a long time there has been a demand for the production of blast furnace lubricants, in the case of smelting in the range of low temperatures of around 400 "C to 600" C have improved grain disintegration properties. It is known that in mechanical-technological tests on iron ores and iron ore agglomerates - sinter and pellets - certain requirements are made. If the required limit values are not met, corrective measures must be taken because a reduction disintegration of the starting materials is known not only to technical difficulties for the furnace control means, but also significant economic disadvantages for the production of pig iron are the result. For corrective actions where, among other things, Changes in the basicity values be brought about, proposals were made, but their realization with higher Use and operating costs is connected. Apart from that, despite the corrective actions often still not meeting the demands made on the iron ore agglomerates with regard to the requirements to achieve strength and abrasion. In addition, the reduction disintegration (grain disintegration) the iron ore agglomerates increase after a short storage time and then during use in the blast furnace or low shaft furnace is again very high. The invention according to the main patent 3242086 was therefore the task is based on a method to minimize the grain breakdown in blast furnaces or low shaft furnaces used to create iron ores and iron ore agglomerates in which in the temperature range the incipient reduction eliminates or reduces the tendency towards grain disintegration will. According to the teaching of the main patent, this problem was solved by that the iron ores before smelting or iron ore agglomerates after production and treated with solid and / or liquid reagents before smelting, which have halogens or halogen-containing compounds. Only by adhering to the method according to the invention in accordance with the teaching the main patent, a relatively simple treatment of the filler materials by immersion, Spraying or powdering, show this as a result of the treatment depending on the type of Möllers, of the reagents according to the invention used and their concentration are different Effects that lead to the complete avoidance of grain disintegration. The method according to the main patent can therefore improve the usability of iron ores or iron ore agglomerates, in particular with regard to their strength and the tendency to wear in blast furnaces or low shaft furnaces is significantly improved will. It has also been found that it is possible with agglomerates with suitable mechanical strength, but poor reduction strength values, to improve their reduction strength values considerably if they are one according to the invention Treatment. The additional patent also has the same task as stated above of the main patent. There is another solution to this problem posed in the method specified in the preamble of claim 1 in that the for Agglomerate production used raw materials before agglomeration with one of the Reduction decay eliminating or reducing reagent to be treated. That Product manufactured using this process is characterized by good disintegration values the end. In addition, the increase is typical of iron ore agglomerates the reduction decay counteracted after a certain period of storage. According to this process, starting ores or their mixtures are presented smelting with halogens or deals with their connections. The addition in according to the invention Process used halogens or their compounds, based on the iron content of raw materials to be in the range of 0.05 to 4%. According to the invention, the reagents intended for treatment in solid and liquid form or as Suspension can be used.