JPS6177651A - Accelerator for cold pellet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an accelerating agent for cold pellets, and more specifically, a method for processing fine iron ore (hereinafter referred to as fine ore) generated during mining. Related to quick setting agent for cold pellets.

[Prior art]

In recent years, the amount of iron ore used has increased rapidly, reserves of high-quality iron ore have decreased, and the development of ore processing technology has made it possible to obtain high-grade fine ore. Pellets of fine ore were mainly made into fired pellets, which were made with an appropriate moisture content using a drum-type or pan-type granulator, and then fired after granulation.
From the viewpoint of energy saving and environmental protection, the calcination process is omitted and a cold pet method is used in which ordinary Portland cement is used as a binder.

[Problem that the invention seeks to solve]

Icgf/, L2 is required.

However, when Portland cement is used as a binder, a curing period of 7 to 14 days is required until a predetermined strength is obtained, and the pellets are often pulverized while being held horizontally.

[Means for solving problems]

The present inventors have conducted various studies in order to develop the strength of pellets in a short time and solve the above problems, and have completed the present invention.

That is, the present invention is a quick setting agent for cold pellets comprising calcium aluminate, divalent metal hydroxide, and monovalent metal carbonate.

The present invention will be explained in detail below.

Calcium aluminates (hereinafter referred to as CA) used in the present invention include 3CaO"AJ203, 12cao.
7Aj203゜Ca0-Aj203, Ca0・2A
J203 and Cll0"6A1203, etc. are crystalline and amorphous. /AAI20 in CA
3, the higher the molar ratio, the stronger the rapid setting. If the aO/molar ratio EIO is low, the rapid setting will be weak. Therefore, the /A, 203 molar ratio is preferably from 0.5 to 4.0, more preferably from 1.0 to 2.5.

Examples of divalent metal hydroxides (hereinafter referred to as M(OH)2) include calcium hydroxide and magnesium hydroxide.

Examples include iron hydroxide, hydrated zinc, manganese hydroxide, etc.
Calcium hydroxide is economically preferred.

The amount of M(OH)2 added is 10 parts by weight per 100 parts by weight of CA.
-200 parts by weight is preferred, and 50-150 parts by weight is more preferred.

As monovalent metal carbonate (hereinafter referred to as M2CO3),
carbonic acid) IJum, potassium carbonate, etc.
Sodium carbonate is preferred from the economic point of view.

The amount of M2CO3 added is 10 to 100 parts by weight of CA.
100 parts by weight is preferred, and 20 to 50 parts by weight is more preferred.

The reason why we decided to use CA, M(OH)2 and M2CO3 in combination in the present invention is because the properties of pellets at high temperatures (hereinafter referred to as high temperature properties 5), which are important when actually used in a blast furnace, are It becomes defective. That is, fine ore pellets need to have good pellet properties at room temperature and high temperature properties, and in particular have a high alkaline content in the ingredients (if this happens, damage to the blast furnace will become a serious problem).

The alkaline content in the cold pellets is preferably about 0.1% by weight or less. 80 more. Both the sulfur content and chlorine content have an adverse effect on the blast furnace.

The present invention suppresses these harmful components as much as possible.

A quick setting agent consisting of CA, M(OH)2 and MgCO3 is used together with a hydraulic substance such as cement to granulate fine ore into cold pellets.

Hydraulic substances include ordinary portland cement, blast furnace cement, 7 lithium cement, silica cement,
Examples include granulated blast furnace slag and converter slag. From a physical standpoint, ordinary cement is preferable, but from an economic standpoint, it is preferable to use industrial by-products, and granulated blast furnace slag is even more preferable.

The mixing ratio of the quick-setting agent and the hydraulic substance of the present invention is preferably 1 to 20 parts by weight of the quick-setting agent to 100 parts by weight of the hydraulic substance.
More preferably 3 to 10 parts by weight.

The amount of the hydraulic substance added is preferably 6 to 15 parts by weight, more preferably 5 to 12 parts by weight, per 100 parts by weight of fine ore. If the amount of the hydraulic substance added is less than this, the strength development will be poor, and if it is more than this, the content of the active ingredient will decrease and the benefits will decrease.

The method of adding each component of the quick-setting agent and the hydraulic substance is not particularly limited, and the order of addition is not particularly limited.

In order to improve the workability and strength properties of the mixed material, commonly used cement admixtures such as cement water reducers, retarders, and AE agents can be used in combination.

Also, monovalent sulfate salts, aluminates, and hydrogen carbonates.

Phosphates and the like can also be used in part.

〔Example〕

The present invention will be further explained below with reference to Examples.

Example 1 Table 1 Experiment/166-15 were blended and kneaded for 3 minutes in a mortar mixer (JISR-5201).

Then 2X2X8c! Cast in rL formwork, 20°0f
iE curing was performed. Handling time and compressive strength were measured. The results are shown in Table-2.

Materials used〉 Powdered ore: Hematite ore limestone: Commercial product Hydraulic substance A: Ordinary Portland cement, manufactured by Denki Kagaku Kogyo ■ 1 B: Granulated blast furnace slag Brain 5020 CT
rL″″/gCA: Pulverized product melted in an electric furnace and then blown out and rapidly cooled Ca (OR)2: Calcium hydroxide, made by Chichibu lime, Slaked lime Na2C○3: Carbonic acid) IJum, Asahi Glass,
Light ash Next, the mixture of Table 1 Experiment/F67.10 was kneaded for about 3 minutes while adding water with a mortar mixer, and then a small amount of water was added dropwise using a pan-shaped granulator (inner diameter 60α). The granulated pellets were granulated to obtain pellets with an outer diameter of 10 to 20 cIrL, and air-dried at 20''C for 7 days. The shrinkage properties were measured.The results are shown in Table 3.

The measuring method was as follows: 200g of pellets were placed in a crucible with an inner diameter of 4.8cm with ten 0.8cm holes drilled in the bottom, and approximately 30g of coke with a size of 1.1 steps was placed in the upper and lower parts of the crucible.
Packed to the thickness of CrIL. The furnace was heated at a heating rate of 10°V in a nitrogen atmosphere, held at 800'C for 10 minutes, and then heated with reducing gas of 30% CO and 70% N2 at 6.14°C.
Flowing Ne10, heating rate to 1500°C at 5'C/min.
The temperature was then increased to 1500'C.

The reduction rate was determined from the analytical values of CO and CO2 in the outlet gas.

Comparative Example 1゜Example 1 except that it was blended as in Table 1 Experiments 161-5
I did the same thing. The results are also listed in Table-2.

Next, the high temperature properties of experimental rot 1 were examined, and the results are also listed in Table 3.

〔Effect of the invention〕

As mentioned in 5 above, when the quick setting agent for cold pellets of the present invention is used, it is possible to obtain strength comparable to that of several days of curing in a few hours compared to conventional cold pellets made only of ordinary Portland cement, so the process is greatly simplified. It is economical and does not require much stockyard.

In addition, the high-temperature properties can be expected to be the same or better than cold pellets made using ordinary Portland cement.

[Brief explanation of the drawing]

The drawing shows an example of a device for measuring the high temperature properties of cold pellets. sign

Claims (1)

[Claims] 1) A rapid setting agent for cold pellets consisting of calcium aluminate, divalent metal hydroxide, and monovalent metal carbonate.