SU761590A1 - Method of annealless pelletizing of materials - Google Patents

Description

The invention relates to the field of ferrous metallurgy and can be used for agglomeration of various iron ore materials.

Known agglomeration methods chemically bonded with iron materials used ⁵ use of hydraulic binders (cement), including its mixing with the ore component pelletizing (briquetting) and subsequent uproch- nenie pieces at normal temperatures, steam curing at about normal pressure or autoclaving

AND·

The disadvantage of these methods is relatively poor quality ₁₅ pieces of reduced strength, increased soder- 'zhanie cement, reducing the iron content in the piece, which is caused by a low degree of utilization of potential binding properties of cements.

Closest to the proposed

technical essence and achievable

the result is a method of obtaining

2

unbaked pellets, which is as follows.

The ore component (dry or wet) and the cement are mixed and mechanically activated in rod mills, the charge is further pelleted in pan granulators. Pellets with the purpose of preventing their sticking together are poured with concentrate, the weight of which reaches 3040% of the weight of pellets, the mixture obtained is loaded into a bunker, where it is kept for 24 hours. The mixture is then released from the bunker and sent to screening, in which the pellets are separated from the concentrate and transferred to other silos for additional hardening during the week, but without refilling them with concentrate. The final hardening of the pellets is carried out in an open warehouse over the next 2-3 weeks. The total duration of hardening of the pellets is 3-4 weeks [2].

The disadvantage of this method is the low strength of lumps and increased cos 761590 4

holding iron in them due to the high consumption of cement.

The purpose of the invention is to improve the quality agglomerated product.

This goal is achieved by the fact that the cement bond before mixing is hydrated at a water-cement ratio of 0.25-0.90 and simultaneous mechanical activation to a content in cement of 5-20 wt.% Chemically bound water. )

The method is as follows.

Cement and water are mixed in a weight ratio equal to 0.25-0.90, and kept to reach 5-20% Chemically bound water in cement, after which it is mixed with iron ore material. Pellets or briquettes are obtained from the charge in the usual way. by heating at normal temperatures, steam curing under atmospheric pressure or elevated pressure steam or heated suyzhoy, ί minimum degree of hydration and the water-cement ratio of ₂₅ is usually taken during pelletization blend. The maximum degree of hydration is taken during briquetting. In the latter case, the highest water-cement ratios are selected, and the cement paste is subjected to mechanical activation.

These differences are explained by the peculiarities of the process of work and briquetting. Palletizing is a fairly time-consuming process. Increasing the degree of cement hydration dramatically reduces the time of its setting, and the work does not have time to work out before the embedding of the cement ligament begins, 49 Making briquettes much faster And can be carried out on quick-setting cement. In turn, “such a binder can significantly increase the strength of briquettes. 45

In briquetting experiments, a binder (Portland cement) of Sukholozhsky cement plant is mixed with water (water-cement ratio is 0.7-0.9), loaded into an M-240 vibrating mill and treated there until 18-20% of chemically bound water is formed in cement. Then the cement in the amount of 5-10% is mixed with iron ore material and is briquetted with a pressing force of 100150 kg / cm and a moisture content of 10-15%, after which the briquettes are kept at ordinary air temperatures for 28 days. In some cases, the briquettes are heated to 100 ° C for 10 minutes before exposure to air.

In experiments with obtaining pellets the port, land cement is mixed with water at a water-cement ratio of 0.25 and is kept for 2 hours at ordinary temperatures, during which the amount of chemically bound water reaches 5.5–8.5%. Then, the amount of cement in the amount of 12.5% is mixed with iron ore materials, the charge of the weight of 4 kg is moistened and loaded into a rod mill with dimensions of 13 ”V = 300x450 mm, where it is activated for 5 minutes. In separate experiments, the charge is not activated. After that, the mixture is passed through a sieve with holes of 1.0 mm and pelletized. Palletizing is carried out on a drum granulator with a diameter of 400 mm 20 minutes. The size of the pellets is 10-20 mm, for testing, samples are taken with a diameter of 14-16 mm. The pellets are strengthened during normal hardening (in a desiccator over water at 20-25 ° C). and test them in 7-28 days (respectively NT ^ and NT ^).

At the same time carry out control experiments on pelletizing and briquetting in accordance with the known method.

Characteristics of some of the materials used and the results of the experiments are presented in table. 1 and 2. _

Table 1

Chemical composition

materials used in the research, wt.% TGMaterial R& . Reo Re ₂ 0e Sao No. £ 0 5-02 Αε 9 S'OVSCH Ppp. one 2, 3 four uh b 7 eight 9 · ten eleven groundland cement Sukholozhsky plant 4,10 0.27 5.56 62.4 2.1 22.1 4.55 0.10 0.76 A mixture of blast furnace blast furnace and open-hearth gas purification 42.2 5.66 54.0 7.14 3.50 10.0 4.0 0.22 6.70 12.2

five

76] 590

6

[Continued table. one

one 2 B four ^five 6 7 eight . 9 YU "-> 1 Furnace dust 46.7 9.16 56,6 7.72 4.89 7.34 3.00 0.28 4.61: 8.57 Sludge sludge • factories 46 <55 2.25 64.0 10.30 0.49 9.62. 1.55 0.54 3.90 Not specified

is an

15 ,.;·.···.·

I Taba yats * 2;

Results tested

on bezbrozhngovomu hardening of iron ore materials

one A mixture of blast furnace blast furnace and open-hearth gas purification Proto-type e " 3.0 10.0 Briquettes - 48 76 74 98 112 150 - 2 Also Prepayment "· 3 Sludge sludge my 0.8 20 3.0 Also - 128 143 319 - four factories Collar Also 0.7 20 5.0 • ·· * · "· · t · 130 160 301 - five great dust A mixture of blast-furnace and 'open-hearth, goooochisTki dust in relation to 0.9. 20 5.0 '"·" * Ββ - 64 146 160 - 6 1: 1 performance Sludge agglobabrihi and flue dust in the relationship 9 0.8 20 5.0 · "· • but 140 150 280 - '1: 1 0.8 . 20 5.0 e ^r F "" In 112 144 274 -

‘761590 ...... 8

Continued table. 2

F? *

Example Iron ore charge Way hardening Conditions of pre-hydration of cement Cement consumption,% Conditions manufacturing  one Compressive strength, kg / cm * (kg / cool.), Through, days Attitude -82Ά & - cement The amount of chemically bound water in cement,% 2 h one 3 t 28 7 7 ” A mixture of blast furnace and open-hearth eight gas cleaning The mixture of house and sludge x) 0.8 20 5.0. 150 174 210 365 at Open-hearth furnace - gas cleaning type Slurry mixture blast furnace and pre-marten lagai— 14.0 Oka you- - · ten one 70 gas cleaning my ** 0.25 0.5 12.5 Okay f » - 22 s 92 ten Also Also 0.40 8.5 12.5 Also - ·· 33 102

x) Heating 10 mive xx) Without mine activation

Thus, the proposed method possesses a number of technical and economic "PreMEs" in front of the known. So, with

the same duration of the hardening cycle the strength of the finished pellets

* (after 28 days) increases by 30-50%

(Table 2, examples 8.9 and 10) while reducing the consumption of cement by 1.5 abs.%, 10.7 rel.%. The latter leads to an increase in the iron content in the pellets from 35.9% to 36.25%. Accordingly, the briquette strength is increased by 1.5-2.0 times ^45} while increasing iron content of from 33.55 to 37.8% (Table. 2, Examples 1 and 2). A significant effect, achieved by the proposed method, is due to the fact that in briquettes and pellets immediately ⁵⁰

"after them, a significant number of neoplasms acting as additives for hardening accelerators (primers) are contained in the preparation.

• χ ·. *

TsNIIPI Order 6070/10

Claims (1)

Claim The method of unburned agglomeration of materials, including preliminary hydration of the cement ligament, mixing it with the ore part, agglomeration of the charge and subsequent hardening, which is characterized by the fact that, in order to improve the quality of the agglomerated product, the ligament is mixed by mixing with a water-cement ratio of 0.250.90 and simultaneous mechanical activation to cement content 5-20 wt.% Chemically bound water.