PL151231B2 - A method of activating spicy-burnt lime from Triassic raw materials - Google Patents

Description

REPUBLIC PATENT ^DESCRIPTION POLAND OF ^THE PROVISIONAL PATENT

OFFICE

PATENT

RP

Provisional patent additional to patent No. - Filed: 88 07 12 (P. 273736)

151 231

Int. Cl. ⁵ C04B 2 / β2 reading room '

Customer Office

Priority Application announced: 89 04 17

Patent description published: 1991 01 31

Creators of the invention: Henryk Kwiecień, Kazimierz Jędras, Marian Uchwacz

Authorized by a provisional patent: Institute of Mineral Building Materials in Opole - Branch in Krakow,

Cracow, Poland)

A method of activating spicy-burnt lime from Triassic raw materials

The subject of the invention is a method of activating hot-burned lime from Triassic raw materials for the needs of the cellular concrete industry.

There is a known method of producing quicklime from raw materials of various geological origin, meeting the requirements for the production of cellular concrete specified in the Polish standard PN-86 / B-30020. According to this standard, lime slaking time is within 10 to 30 minutes, while the slaking temperature should not be less than 60 ° C. In this method, it is possible to influence to some extent the quality of calcination of the limestone and thus the properties of the obtained lime. However, with some types of raw materials, especially of Triassic origin, the controllability of the firing process is limited. The Triassic raw materials generally have a chemical composition that gives theoretically a chance to obtain a high percentage of lime, which is confirmed by laboratory tests of burning these raw materials in an electric furnace. However, the existing diverse structure of Triassic limestones causes serious difficulties in obtaining homogeneous lime with a short or medium slaking time, especially in coke-fired shaft kilns. It is practically impossible to obtain homogeneous lime in these kilns from certain layers, batches of Triassic raw material deposits. At best, a mixture of hot and medium-burnt lime is obtained, which, ground in mills and averaged, gives a product with a slaking time of 30 to 50 minutes and a slaking temperature in the range of 58 ° C to 63 ° C, which does not meet the requirements of cellular concrete producers.

However, in rotary kilns, where limestones of Devonian or Carboniferous origin are used as raw materials, lightly burnt lime is obtained, highly active, with a slaking time of 1 to 8 minutes and a slaking temperature within the range of 65 ° C to 80 ° C. Such lime cannot be used for the production of cellular concrete due to the too short time of slaking this lime, which must be synchronized with the process of releasing hydrogen gas in the process of growing the concrete mass. Limes burnt from Jurassic, Carboniferous and Devonian raw materials in shaft kilns also have a much shorter quenching time.

The essence of the invention is the activation of the process of hydration of slowly slaking quick-burnt lime particles from Triassic raw materials by using and adding lightly burning lime2

151 231. The method of activating the quicklime according to the invention consists in grinding the quicklime with the lightly quicklime used in an amount of 10-40%. As a result of the activation of sharply burnt lime with lightly burnt lime, an increase in the temperature of the reaction medium is achieved in the first minutes after mixing the aerated concrete mix and an increase in the concentration of Ca (OH) 2 solution and suspension, i.e. an increase in the alkalinity of aerated concrete mixing. Both of these factors influence the early initiation of the course of the hydration reaction, which in turn shortens the slaking time and increases the slaking temperature of the Triassic quicklime. It is also important to choose the proportion and method of making a mixture of two types of lime, i.e. sharply burnt lime from Triassic raw materials and lightly burnt lime, in order to obtain treatment properties or improve the parameters of lime for the production of cellular concrete. The increase in the slaking temperature of the mixture does not result from a simple heat balance of the mixture, but is higher due to the acceleration of the hydration process of the sharps lime particles at elevated temperature in the initial phase of the reaction and due to the activation of the burnt particles. The factor of the formation of hydration seeds in the first 5 minutes of the hydration process and the alkalization of the environment in this period of time are of great importance here.

Lightly quicklime with a slaking time of 5 to 10 minutes and a slaking temperature of at least 70 ° C, preferably 75 ° C should be used as the activating lime. Preferably, lightly quicklime obtained from Devonian, Carboniferous or Jurassic limestones should be used.

Example 1: Lime is produced by a known method for the production of cellular concrete.

So far, with a medium-intensive firing process in the so-called coke-fired "100" high-shaft kilns are obtained from Triassic raw materials, at best, a mixture of hot and medium-burnt lime with a misfire content of about 5 wt. This lime ground in mills and averaged gives a product with the following properties:

- extinguishing time - 30 to 50 minutes

- extinguishing temperature - 58 ° to 63 ° C

- active CaO + MgO content - 78 to 82 wt.%.

Only in some cases such a product meets the minimum requirements of cellular concrete producers.

On the other hand, in other plants using limestone of Jurassic, Devonian or Carboniferous origin, lightly burnt, highly active lime can be obtained. This lime obtained from Carboniferous limestone fired in rotary kilns has the following properties:

- extinguishing time - 1 to 8 minutes

- extinguishing temperature - 65 ° to 80 ° C

- content of active CaO + MgO - 82 to 92% by weight.

Such lime cannot be used for the production of cellular concrete because the slaking time is too short, which makes it impossible to synchronize the slaking process with the process of hydrogen gas release during the expansion of cellular concrete mass.

Example II. It relates to the activation of lime used for cellular concrete with the method according to the invention.

For hot-burnt lime from coke-fired "100" series shaft kilns, which were fired from Triassic raw material from the "Tarnów Opolski" deposit with the following properties:

- extinguishing time - 40 minutes

- extinguishing temperature - 56 ° C

- content of active CaO + MgO - 82% by weight

151 231 3, lightly burnt lime from rotary kilns was added, obtained from the Carboniferous raw material from the "Czekkowice" deposit, with the following properties:

- extinguishing time - 8 minutes

- extinguishing temperature - 77 ° C

- active CaO + MgO content - 85% by weight

Activation of the lime intended for the production of cellular concrete was performed by dosing the ball mill with lime burnt from Triassic raw material in the amount of 70% by weight and lightly burnt lime, calcined from the carbonate raw material, in the amount of 30% by weight. After joint grinding, ground quicklime was obtained, with the following properties:

- extinguishing time - 22 minutes

- quenching temperature -61 ° C

- content of active CaO + MgO - 83 wt.%.

The obtained product is fully suitable for the production of cellular concrete, meeting the requirements of the Polish standard PN-86 / B-30020 from two types of lime not suitable for this purpose.

Claims (2)

Patent claims 1. A method of activating hot-burnt lime from Triassic raw materials, characterized in that the hot-burnt lime is milled with a lightly burnt lime activator with a slaking time of 5 to 10 minutes and a slaking temperature of not less than 70 ° C, in an amount from 10 to 40 % by weight based on hot lime from Triassic raw materials. 2. The method according to p. The process of claim 1, wherein the activator is lightly quicklime obtained from Devonian, Carboniferous or Jurassic limestones with a slaking temperature of 75 ° C.