RO127643A2 - Process for preparing building cements with admixture of sludge bed mining sterile - Google Patents

Abstract

The invention relates to a building cement composition. According to the invention, the composition comprises 74.85% limestone, 22.54% clay and 2.59% sludge pond mining sterile which has the role of siliceous and/or ferruginous correction material and has the following chemical composition:77.79% silica, 5,28% aluminium oxide, 8.65% iron oxide, 0.81% calcium oxide, 0.39% magnesium oxide, 0.13% sodium oxide, 1.52% potassium oxide, 0.08% manganese oxide, 0.49% total sulphur, 1.19% sulphur oxide, 0.01% sulphides, 4.13% ignition losses.

Description

The invention relates to a product for obtaining construction cements by the addition of tailings mine tailings.

The mining tailings, quarried in the tailings ponds of the preparation plants, represent the residues obtained from the processing of the various deposits of useful mineral substances. These are, at present, an environmental polluting factor. Depending on the physico-chemical characteristics of the tailings deposited in the tailings ponds (settling) they can be reprocessed or used as additives in different products.

Additions commonly used in the manufacture of cement are of two types: natural and artificial. The natural additives used either for the correction of the crude mixture, or as a regulator of the active or hydraulically active time, are rocks of the type: sand, gypsum, limestone, natural puzztolane etc. The artificial additives resulting as by-products from other industries and which can be used in the manufacture of cement, in the crude mixture or in the grinding of the clinker are: pyrite ash, processed iron ore, ultrafine silica, thermocentrifuge ash, furnace slag, etc.

Currently, the following additions are currently used in cement plants in Romania:

in the crude mixture: pyrite ash, sand;

when grinding cement: gypsum, limestone, natural puzzles, slag.

It is noteworthy that both the alignment with the European norms, as well as the results obtained from technical and economic analyzes carried out in the various researches in the field, led to the idea of diversifying the additives used in the manufacture of cement.

The use of pond tailings as additives in the manufacture of cement is determined by the following requirements:

obtaining a clinker in accordance with the conditions imposed by the quality standards in force by using the sterile to correct the raw mixture;

making some cement with additions to the grinding in order to obtain the physical and physical - mechanical characteristics of the cement according to the norms in force;

full awareness of economic and environmental benefits.

INCDMRR - ICPMRR

General Manager Dr. ing. Viorica Ciocan

P. 1

V ⁰ j ¹ f ^ °. ¹ ₂ μπι ⁴ '' -xfyMA / MMA iy

The use of tailings tailings in cement manufacturing can lead to the following advantages:

development of the recycling process as a solution in the fight against environmental pollution, but also a source of important economies a way of managing the solid mineral residues from settling ponds, with the possibility of transforming them into usable resources.

The technical problem, which arises, is to determine the chemical characteristics of the tailings pond that can be used to obtain the cement and the dosage ratio of each constituent.

The process according to the invention solves this problem by determining the chemical characteristics of the tailings pond which can be used as a silicon and ferrous corrector in obtaining the cement and its dosage ratio.

The process according to the invention is further presented by the characteristics of the raw material and the tailings tailings, by the percentage dosage of the constituents as well as the characteristics of the cement obtained.

The technological steps of processing the cement in which the mineral tailings pond is used as a correction addition, follows the following stages: preparation of raw materials, analysis of the mixture of raw materials by dosing of components, grinding of the mixture of raw materials, clinker of the mixture of raw materials, obtaining clinker. , grinding of cement.

The cement obtained was made by mixing the following products:

- tailings mine tailings (from the Zlatna mining operation - settling pond no. 1) with the following chemical composition: PC = 4.13%; SiO ₂ = 77.79%; AI2O3 = 5.28%; Fe ₂ O3 =

8.65%; CaO = 0.81%; MgO = 0.39%; Na ₂ O = 0.13%; K ₂ O = 1.52%; MnO = 0.08%; Total S =

0.49%; SO ₃ = 1.19%; Sulfides = 0.01%.

- the silico-alumina feedstock, is represented by a clay, which geologically belongs to the Eocene. This type of clay, mixed with high purity limestone, results in a wide range of cements according to the standards in force.

The chemical composition of the clay is as follows: PC = 11.59%; SiO ₂ = 50.61%; AI2O3 = 13.87%; Fe ₂ O ₃ = 6.55%; CaO = 10.59%; MgO = 1.70%; Na ₂ O = 1.52%; K ₂ O = 2.50%;

MnO = 0.08%; Total S = 0.49%; SO3 = 0.08%; Sulfides = 0.02%.

the calcareous raw material is a Jurassic limestone, of high purity, having a high content in CaCO3. The chemical characterization of the limestone aims first and foremost,

INCDMRR - ICPMRR

General Manager Dr. ing. Viorica Ciocan

P. 2 in

CV 2 Ο 1 Ο - Ο 1 Ο 9 4 - 1 1 “11- 2010 the basic elements that take part in the formation of minerals with hydraulic properties, respectively CaO, SiO ₂ , AI2O3, Fe ₂ O _3j but also other secondary elements that can damage to the quality of the cement or can adversely affect the functioning of the technical installations - MgO, T1O2, SO3, Na2O, K ₂ O, CI.

The chemical composition of the clay is as follows: PC = 43.47%; S1O2 = 0.42%; AI2O3 = 0.51%; Fe ₂ O ₃ = 0.20%; CaO = 53.48%; MgO = 0.80%; Na ₂ O = 0.42%; K ₂ O = 0.13%; Total = 0.03%; SO ₃ = 0.00%; Sulfides = 0.03%.

The dosage of materials for obtaining cement are: limestone 74.85%, clay: 22.54%, mineral tailings pond: 2.59%.

The clinker resulting from the burning of the mixture of raw materials, at a temperature of 1450 ° C, is of good quality having high contents in tricalcium silicate. The chemical characteristics of the clinker based on which the modular composition was determined are: PC = 0.22%; SiO ₂ = 21.92%; A1 ₂ O ₃ = 5.47%; Fe ₂ O ₃ = 3.59%; CaO = 68.13%; MgO = 0.4%; Na ₂ O = 0.14%; K ₂ O = 0.02%; Res. ins HCl-Na ₂ CO ₃ = 0.16%

The modular composition of the clinker: Msi = 2.42, May = 1.52, St = 0.96.

The cement obtained from clinker with the addition of high purity gypsum has the following physical-mechanical characteristics:

Specific surface area Blaine (cm / g): 3,500

Water of standard consistency (%): 24.2

Start time (min.): 190

End time (hours): 4

Stability (mm): 0,0

- Bending strength at 2 days (N / mm ² ): 3.50

Bending strength at 7 days (N / mm): 5.84

28-day bending strength (N / mm): 8.23

Compression resistance at 2 days (N / mm ² ): 15.4

Compression resistance at 7 days (N / mm): 32.9

Compressive strength at 28 days (N / mm): 54.9

Resistance class: 42.5 N

The cement obtained by the addition of mining tailings from the pond is in a higher strength class - 42.5 N, which can be used as a construction material.

The use as a correction additive for the silicon and / or iron content in the manufacture of construction cements may also be applied to other types of tailings, provided they have a chemical composition close to that experienced.

Claims (1)

1. Process for obtaining construction cements with the addition of tailings mine tailings, characterized in that siliceous and ferrous fillers are used, for cement manufacture, a tailings mine tailings, with the following main chemical composition: SiO ₂ = 77.79%; AI2O3 = 5.28%; Fe ₂ C> 3 = 8.65%; CaO = 0.81%; MgO = 0.39%; Na ₂ O = 0.13%; K ₂ O = 1.52%; MnO = 0.08%; Total S = 0.49%; SO3 = 1.19%; Sulfides = 0.01%; losses by calcination = 4.13% and in a dosage ratio of materials for obtaining cement of: 74.85% limestone, 22.54% clay, 2.59% tailings mine.