JPS58223610A - Process for recovering flaky graphite from iron mill dust - Google Patents

Abstract

PURPOSE:To recover high-quality flaky graphite from the dust of an iron mill, in high efficiency, by pretreating and floating the dust, adding sulfuric acid thereto, and again carrying out the flotation. CONSTITUTION:The collected dust is subjected to the treatments such as sieving, grinding, classification, etc. to remove the coarse particles and heavy impurities, repulped to a solid concentration of about 12%, sent to the conditioning tank, added with a collector, frother, etc., left to stand in the tank for about 3-5min, and subjected to the primary flotation in the flotation apparatus to remove the most part of lime and iron. If necessary after repeating the above steps, the obtained float is ground with a ball mill, added with sulfuric acid to adjust its pH at 4-7, and sent to a flotation apparatus to separate the free lime in the form of gypsum. High-quality flaky graphite can be obtained by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering high-grade flaky graphite from collected dust containing precipitated carbon generated from the pretreatment process of hot metal converter blowing in a steel factory.

In your steel factory, for example, blast furnace hot metal is transported to the steelmaking factory using a hot metal transport vehicle. During this time, the temperature of the hot metal decreases slightly, and the solubility of the carbon dissolved in the hot metal decreases as the temperature decreases, and it precipitates as flaky graphite. This scaly graphite is violently scattered from the hot metal when exposed to shocks such as boiling and flow during pre-furnace desulfurization work and hot metal tapping from a hot metal car, and it also generates lime powder and iron fume. It is sucked into a dust collector together with fine iron powder. Therefore, flaky graphite complemented in such a state is generally of low quality, with iron, lime, etc. intervening between the flaky graphite crystals. Therefore, it is difficult to utilize the flaky graphite that is generated, and the reality is that most of it is simply abandoned.

The present invention focuses on the value of flaky graphite, and provides a method for efficiently recovering flaky graphite from recovered dust, which has heretofore been discarded.

Table 1 shows an example of component analysis by particle size of typical collected dust.

Margin below According to this, carbon content is considerably concentrated in the coarse particles. However, depending on the type of dust, the amount of coarse particles is small, so the amount of carbon is small, and targeting only the scaly graphite in the coarse particles may be unfavorable in terms of yield.
It is necessary to establish a collection method suitable for each type of dust. Furthermore, according to microscopic observation, the presence of inclusions in the flaky graphite was observed, indicating that it was not isolated as a single substance.
It was done. Therefore, in this dust treatment, it is necessary to efficiently separate the black ship and impurities by grinding ore, and to recover the separated flaky graphite by flotation.

The degree of crystal development of scaly graphite contained in dust varies depending on its formation conditions. Generally, well-developed coarse graphite is tabular, while poorly developed fine-grained graphite has a complex shape with curved parts. There are fine impurities inside. Therefore, when attempting to separate graphite and impurities, the particle size of the graphite must be determined.

It is necessary to determine the grain size of polished ore based on the shape, coexistence state with impurities, etc. In other words, if the crystals are well developed and coarse, the grain size may be large and the coarse flotation can be sent directly to the next process, but if the crystals are poorly developed, the flotation may be further carried out after rough separation. It is necessary to perform ore polishing → conditioning → flotation (middle path λ) before sending it to the next process.

In addition, single-edged flaky graphite is a combination with lime, iron, etc., so when it is reacted with sulfuric acid, lime easily becomes gypsum, and at the same time, iron is also removed from flaky graphite along with gypsum as lime becomes gypsum. The flaky graphite separates and becomes a single substance. However, in order to carry out this reaction efficiently, it is necessary to grind the particles in advance to increase the surface area of the particles.

Next, sulfuric acid was added to the floating ore obtained as described above, the pH was adjusted to ~7, and the reaction was stirred. After flotation treatment, the scaly black ships separated into individual pieces were floated very efficiently. High-grade flaky graphite can be obtained by refining and flotating this floating ore several times.

The reason why the pH is adjusted by adding sulfuric acid is that the free lime contained in the dust becomes gelatinous and produces graphite 4.m (.)
χt, i7 The purpose of recovering graphite products (M to lower sγ) is to change the shape of the dough into 41:I to separate it from graphite. Therefore, it is better to increase the sulfuric acid flow force [1@, for example, to increase the amount of gypsum produced by increasing the p11 to the strongly acidic side (for example, pl (/~3), and then neutralizing it with f1 ash to increase the amount of gypsum produced.) However, as the amount of gypsum produced increases, gypsum precipitates in the pipes and in the flotation machine, causing problems in operation 1, so the amount of gypsum produced decreases by 6-j-r. It is preferable to use as little as possible.Therefore, neutralization with lime
It is preferable to adjust the ratio to 11≠-7 (1 for sulfuric acid addition IJII only).

Next CJ, Flowchart for recovery of flaky graphite by the method of the present invention I
・σ)−・An example is shown in the male side drawing.

To explain this, first, the collected dust is treated as it is or subjected to G1 sieve & J, grinding 2 classification, etc. to remove coarse grain impurities and heavy impurities, resulting in a solid concentration of approximately 72%.
After being repulped, it is sent to a conditioned tank a). In the conditioning tank, conditioners such as kerosene as a seizing agent and MiBC (all trade names) as a foaming agent were added to +111 L, and the mixture was allowed to stay there for about 3 to 30 minutes and then sent to a rough separator to form a primary i? Separation is performed to separate most of the stone UJ< and iron content.

- After the next flotation, the floating ore is sent to a conditioned tank after grinding, and after being subjected to the same conditions as above, it is flotated. This step may be repeated several times if necessary.

Next, the obtained floating ore is ground in a ball mill to increase the surface area in order to enhance the effect of the sulfuric acid treatment, and then sulfuric acid is added to adjust the content to p) Ig~7.

After adding approximately the same amount of seizing agent and foaming agent as in the rough selection to the pH-adjusted valve, the mixture is sent to a flotation machine to efficiently selectively separate the iljl fragmented flaky graphite and the generated gypsum.

” - After drying, the high-quality scaly black ships obtained through careful selection are
It is finely pulverized to a particle size suitable for the intended use, and further purified if necessary, such as hydrochloric acid treatment, to obtain an R final product.

As described above, the present invention performs pre-treatment to remove coarse particles and heavy materials by 9 classifications of polished ore, and then separates and recovers the Qt form of scaly graphite by repeating flotation and scrapping, and also removes dust by adding sulfuric acid. By removing and separating the lime content in the form of gypsum, it becomes possible to economically recover high-grade scaly Kurofune with a high yield from the dust generated during hot metal pretreatment. It can be used as a raw material for high value-added applications.

Example/ Conditions from A to F in Table 1 and 111 (i
According to the above procedure, flaky graphite was recovered.

(1) Part 1. Culm pretreatment sieve fraction G1 3-pinch sieve ■ Classification Sedimentation method ■ Repulp 70 to 20% ■ Grinding ore Small ball mill 13) Row fl-1 ke ■ Condition time 70 to 0 minutes ■ pi-1/, , 2J ■Concentration 72-77% ■Seizure agent Kerosene ■Foaming agent MIBC C) Rough selection flotation machine, 27t FW type flotation machine @flotation time 70-20 minutes D) Polished ore Vibromill polished ore Size -! 00 mesh 50% @ concentration
0～≠θ% E) Condition time 70-20 minutes @ pI-1g～ri ■Concentration 70-75% ■Seizure agent Kerosene ■Foaming agent M I B C F) Middle road flotation Machine 27 t FW type α selection machine @α selection time
20-30 minutes (2) 2nd step A) Polished ore Hypromilno polished ore size -NO00Metsushiko 70% @concentration
20~≠θ% B) p, H adjustment (addition of sulfuric acid) pH≠~7C) Conditions τ] ke■Condition time 75~20 minutes■p f, (J~7 ■Concentration 7~70% [Yes] Complement Agent Kerosene ■Foaming agent M I 13 C ■-)) Selected flotation machine, 27 t P W-type flotation machine @flotation time ≠θ ~ θ min Iu) Dehydration/Washing Jpa) Drying () ) Grinding The carbon grade and carbon distribution of the flaky graphite thus obtained are shown in Table 2 along with the intermediate progress.

Below, scaly graphite was recovered from B dust in Table 1 of Margin Examples as described above.

(1) First step A) Pre-treatment sieving 3 Pharyngeal mesh vibrating screen ■ Grinding
Vibromill ■ Classification Wet cyclone ■ Repulp 70-20% (2) Knee 1. The carbon grade and carbon distribution of the flaky graphite obtained from the culm are shown in Table 3 along with the intermediate progress.

According to the present invention, the quality is 7 to 9 g as shown in Tables 2 and 3.
It becomes possible to recover high-quality scaly black ships with a high yield of 0% or more.

[Brief explanation of the drawing]

The figure shows an example of flow silt recovered from flaky graphite according to the method of the present invention. Patent Applicant Kowa Seiko Co., Ltd. Nippon Steel Corporation Amendment 11th (Method) 1935, October-11-1 1, Kidney, i'r Iil, 2' White
= Iifl Display Patent Application No. 1986-10 + Do-77 2 Name of Invention Method for recovering flaky graphite from steel factory dust a F
Related to mfI Mosuru JK Tobi) Patent applicant name: Kowa Seiko Co., Ltd. 4 agents (7 people) As shown in the attached sheet. Regarding the B dust shown in Table 1 above, flaky graphite was recovered in the following manner. (1) First step A) Pre-treatment sieving 3. Origami mesh screen ■ Grinding
Vibromill ■ Classification Wet Cycling ■ Repulp 70~. 20% (21 second process

Claims (1)

[Claims] The first step is to flotate the dust generated from a steel factory that contains scaly graphite, or to remove coarse particles and heavy materials by grinding and classification, and repeat grinding and flotation if necessary. Then, the floating ore obtained in the first step is treated as it is or after being polished, the pH is adjusted by adding sulfuric acid.
7. A method for recovering scaly graphite from steel factory dust, comprising a second step of recovering high-grade scaly graphite by flotation after adjustment to 7.