【発明の詳細な説明】[Detailed description of the invention]
本発明は焼結鉱品質に悪影響を与える粉鉱石の
反応性を改善して、その悪影響の可及的低減を図
つた焼結原料の前処理方法に関するものである。
焼結原料は各種の粉鉱石、含鉄原料等、通常10
〜13種類のものを夫々５〜20％程度配合し、これ
に高炉操業上要求される塩基度CaO／SiO2が所
定の値となるよう、予め定めたSiO2量に対し焼
結原料量の13〜14％の粉石灰、更にコークス等の
副原料を加え、ミキサにて混合粒造処理を施した
後、焼結を行うこととしている。ところで混合す
る各種原料銘柄中には他の粉鉱石に比較して焼結
鉱の生産性、品質に対し好ましくない鉱石、例え
ばハマスレー・ゴア鉱石、砂鉄等がある。一般に
鉄鉱石を還元した場合の強度劣化の原因として、
結晶の粗大化が知られており、とりわけ鉱石中の
成分Al2O3はボンド部のカルシウムフエライトの
粗大化、シリケートのガラス質化を促進し、ヘマ
タイト周囲の組織を脆弱化するといわれている。
鉱石の操業実績を解析した結果によれば、鉱石中
の成分Sl2O3、SiO2の比と密接な関係があり、
Al2O3（％）×Al2O3（％）／SiO2（％）による算
出値1.5以上の鉱石、例えば前述のハマスレー・
ゴア、砂鉄等が生産性、品質上好ましくない。し
かしながらこれらの鉱石は種々の理由から不可避
的に少なからず配合されるが、これに対する特別
な処置は従来全く採られておらず、単に他の鉱石
と同様に疑似粒子化処理を施し、或いは配合割合
をそれによる悪影響が最小限に留まるよう設定す
るなどの対策を施しているに留まる。
本発明者はこのような焼結の生産性、焼結鉱品
質に悪影響を及ぼす粉鉱石の処理につき実験、研
究を行つた結果、粉石灰を焼結原料全体にわたつ
て均等に混合する外、上述した粉鉱石に対しては
粉石灰との接触機会を増大すべく他の原料とは個
別に0.25mm以下の微粉石灰を配合することにより
その反応性が著しく向上し、焼結生産性、焼結鉱
品質を大幅に向上させ得ることを知見した。
本発明はかかる知見に基づきなされたものであ
つて、焼結鉱品質に悪影響を与える粉鉱石に粒径
0.25mm以下の微粉石灰を５〜15％の割合で配合し
た後、焼結原料として供することを特徴とする。
本発明方法において、焼結鉱品質に悪影響を及
ぼす劣質原料に予め加えるべき微粉石灰の粒径を
0.25mm以下としたのは、これ以上では疑似粒子化
過程でのバインダーとしての機能、比表面積拡大
による反応性並びに鉱石粒子に対する付着性が急
激に低下するためである。また微粉石灰の混入量
を５〜15％としたのは５％以下及び15％以上では
いずれも焼結鉱品質及び生産性向上に対して効果
が少なく、特に15％以上とすると、全焼結原料に
おける塩基度CaO／SiO2が定められているた
め、必然的に装入すべき粉石灰量を低減せざるを
得ず、これによつて全体としての焼結鉱の生産性
及び品質が低下することによる。なお焼結原料は
平均的に２〜５％の範囲でSiO2を含有している
ため、一定量のCaOを添加したときCaO／SiO2
値にばらつきが生ずるが、これに伴う影響は殆ん
ど無視し得る程度である。
次に本発明の実施例について説明する。対象と
した劣質原料は銘柄がSFHであつて、その粒度
分布及び主要成分は表１、２に示す如くであり、
Al2O3（％）×Al2O3（％）／SiO2（％）の値が
1.64である。
The present invention relates to a method for pretreating sintered raw materials, which improves the reactivity of fine ore that adversely affects the quality of sintered ore, and reduces the adverse effects as much as possible. Sintering raw materials include various powder ores, iron-containing raw materials, etc., usually 10
~13 types are mixed at a rate of 5 to 20% each, and the amount of sintering raw material is adjusted to a predetermined amount of SiO 2 so that the basicity CaO/SiO 2 required for blast furnace operation becomes a predetermined value. After adding 13 to 14% powdered lime and auxiliary raw materials such as coke, the mixture is granulated using a mixer and then sintered. However, among the various raw material brands to be mixed, there are ores that are less favorable in terms of productivity and quality of sintered ore than other fine ores, such as Hamersley Gore ore and iron sand. In general, the causes of strength deterioration when iron ore is reduced are as follows:
It is known that crystals become coarser, and in particular, the Al 2 O 3 component in the ore is said to promote coarsening of calcium ferrite in the bond area and vitrification of silicate, weakening the structure around hematite.
According to the analysis of ore operation results, there is a close relationship with the ratio of the components Sl 2 O 3 and SiO 2 in the ore.
Ore with a calculated value of 1.5 or more by Al 2 O 3 (%) x Al 2 O 3 (%) / SiO 2 (%), such as the aforementioned Hamasley
Gore, iron sand, etc. are unfavorable in terms of productivity and quality. However, although these ores are unavoidably mixed in large quantities for various reasons, no special treatment has been taken in the past, and they have simply been subjected to pseudo-granulation treatment in the same way as other ores, or the mixing ratio has not been changed. Measures are being taken to ensure that the negative impact of such changes is kept to a minimum. The present inventor conducted experiments and research on the treatment of powdered ore, which has a negative effect on sintering productivity and sintered ore quality, and found that in addition to uniformly mixing powdered lime throughout the sintering raw material, For the above-mentioned fine ore, by blending fine lime of 0.25 mm or less with other raw materials to increase the chance of contact with the fine lime, its reactivity is significantly improved, and sintering productivity and sintering efficiency are improved. It was found that the concretion quality could be significantly improved. The present invention has been made based on this knowledge, and it is based on this knowledge that fine ore particles having a particle size that adversely affects the quality of sintered ore are used.
It is characterized by blending fine powder lime of 0.25 mm or less at a ratio of 5 to 15% and then providing it as a sintering raw material. In the method of the present invention, the particle size of pulverized lime, which should be added in advance to inferior raw materials that adversely affect the quality of sintered ore, is
The reason why it is set to 0.25 mm or less is because if it is larger than this, the function as a binder in the pseudo-particle formation process, the reactivity due to the expansion of the specific surface area, and the adhesion to ore particles will decrease rapidly. In addition, when the mixed amount of pulverized lime is set at 5 to 15%, if it is less than 5% or more than 15%, it has little effect on improving the quality of sintered ore and productivity. Since the basicity CaO/SiO 2 is determined at It depends. Note that the sintering raw material contains SiO 2 in an average range of 2 to 5%, so when a certain amount of CaO is added, CaO/SiO 2
Although variations occur in the values, the effect associated with this is almost negligible. Next, examples of the present invention will be described. The target inferior quality raw material is the brand SFH, and its particle size distribution and main components are as shown in Tables 1 and 2.
The value of Al 2 O 3 (%) × Al 2 O 3 (%) / SiO 2 (%) is
It is 1.64.
【表】【table】
【表】
このような劣質原料20Kgに粒径0.25mm以下の微
粉石灰を夫々３、５、10、15、20％混入してミキ
サにより十分に混合し、この各劣質原料を重量比
15％、別に用意した各良質原料を重量比85％の割
合で配合し、次いでこの配合原料100部に対し粉
石灰を13部の割合で加え、更にこれに各一定量の
コークス、水等を加えてミキサにより造粒した後
焼結を行なつた。なお参照例として劣質原料に微
粉石灰を全く加えない従来方法、及び劣質原料に
対する微粉石灰の混入量を本発明における設定範
囲を越えた場合についても夫々原料配合割合を同
じにした焼結原料を作製して夫々について焼結鉱
を得、これによつて得た各焼結鉱について、夫々
生産率（Ｔ／Ｄ・m2）、回転強度（％）、コークス
原単位（Kg／Ｔ−Ｓ）、成品中のCaO（％）、CaO
のばらつき（σ）につき調査した。結果は第１図
イ〜ニのグラフに示すとおりである。第１図イ〜
ニはいずれも横軸に石灰配合率を、また縦軸に
は、第１図にイにあつては生産率（Ｔ／Ｄ・m2）
を、第１図ロにあつては回転強度（％）を、第１
図ハにあつてはコークス原単位（Kg／Ｔ−Ｓ）
を、第１図ニにあつては成品のCaO（％）及び
CaOのばらつき（σ）を夫々とつて示してある。
図面から明らかな如く、生産率、回転強度、コー
クス原単位ともに本発明方法を適用した場合に他
の方法よりも格段に優れていることが解る。また
成品中のCaO量及びそのばらつきは事前混合なし
の場合に於いても20％配合した場合においても殆
んど差は無く、単独銘柄への微粉石灰の事前配合
は特に問題ないといえる。
なお上述の実施例は単一銘柄の劣質原料を対象
とした場合につき説明したが複数銘柄の劣質原料
を混合して用いる場合についても夫々の銘柄毎に
予め定めた好ましい割合で微粉石灰を設定して混
入することにより、本発明方法を適用し得ること
は勿論である。
以上の如く本発明方法にあつては焼結鉱品質に
亜影響を及ぼす劣質原料について、予め適切な微
粉石灰を混合して付着せしめた状態で疑似粒子
化、更には焼結を行うこととしているため、劣質
原料はこれに接触せしめられた微粉石灰によつて
その反応性が高められ、焼結鉱品質、焼結生産性
が著しく改善されるなど、本発明は優れた効果を
奏するものである。[Table] Mix 3, 5, 10, 15, and 20% of finely powdered lime with a particle size of 0.25 mm or less into 20 kg of such inferior raw materials, mix thoroughly with a mixer, and calculate the weight ratio of each inferior raw material.
15% and each high-quality raw material prepared separately is mixed at a weight ratio of 85%, then powdered lime is added at a ratio of 13 parts to 100 parts of this mixed raw material, and furthermore, a certain amount of coke, water, etc. are added to this. In addition, sintering was performed after granulation using a mixer. As a reference example, sintered raw materials were prepared with the same raw material blending ratio for a conventional method in which no pulverized lime was added to the inferior raw material, and in a case where the amount of pulverized lime mixed in the inferior raw material exceeded the set range in the present invention. The production rate (T/D・m 2 ), rotational strength (%), and coke consumption rate (Kg/T-S) are determined for each sintered ore obtained. , CaO in finished product (%), CaO
The dispersion (σ) was investigated. The results are shown in the graphs A to D of Figure 1. Figure 1 I~
In both cases, the horizontal axis shows the lime content ratio, and the vertical axis shows the production rate (T/D・m 2 ) in case of A in Figure 1.
, rotational strength (%) in Figure 1B,
For Figure C, coke consumption unit (Kg/T-S)
In the case of Figure 1 D, the CaO (%) of the finished product and
The dispersion (σ) of CaO is shown in each case.
As is clear from the drawings, it can be seen that the production rate, rotational strength, and coke consumption rate are significantly superior to other methods when the method of the present invention is applied. In addition, there is almost no difference in the amount of CaO in the product and its variation whether it is mixed without pre-mixing or when it is mixed at 20%, so it can be said that there is no particular problem with pre-blending fine powder lime into a single brand. Although the above-mentioned embodiments have been explained for the case where a single brand of poor quality raw material is used, even when a mixture of multiple brands of inferior quality raw materials is used, the powdered lime can be set at a predetermined preferred ratio for each brand. It goes without saying that the method of the present invention can be applied by mixing the above substances. As described above, in the method of the present invention, the inferior raw material that has a negative effect on the quality of the sintered ore is mixed with an appropriate amount of pulverized lime in advance and made into pseudo-particles, and then sintered. Therefore, the reactivity of the inferior raw material is increased by the fine powder lime brought into contact with it, and the quality of sintered ore and sintering productivity are significantly improved, so the present invention has excellent effects. .
【図面の簡単な説明】[Brief explanation of the drawing]
第１図イ，ロ，ハ，ニは本発明方法と従来方法
との比較試験結果を示すグラフである。
FIG. 1A, B, C, and D are graphs showing the results of a comparative test between the method of the present invention and the conventional method.