RU2155724C1 - Process lumpy lime - Google Patents

Abstract

FIELD: compositions of lumpy process limes applicable in chemical industry as process raw material, and in metallurgical industry, as fluxes. SUBSTANCE: process lumpy lime contains, wt.%: magnesium oxide 2.5-3.5; sum of iron and aluminum oxides 1.0-1.5; the balance, calcium oxide. Lime density is 2.6-2.8 g/cu.cm. Offered lime due to balanced composition is suitable for use not only in chemical and metallurgical industries but also in construction and agriculture. EFFECT: higher quality of product.

Description

 The invention relates to compositions of lump technological lime used by enterprises of the chemical industry as technological raw materials and in the metallurgical industry as fluxes. Crushed lime in crushed form is used in construction, to neutralize acidic effluents, to deoxidize soils (during autumn and spring plowing) and as an additive to pet food and birds.

 Known lime containing oxides of calcium, magnesium (Linus Pauling, General Chemistry, ed. "Mir", M., 11964, S. 113).

 The disadvantage of this lime is the variety of impurities that create an obstacle to the further use of lime.

 The closest in technical essence and the achieved result to the proposed one is technological lump lime, containing oxides of calcium, magnesium, iron, aluminum and silicon dioxide (Jp, 06157085, C 04 B 2/02, 03.06.94).

 The disadvantage of this lime is the lack of a balanced composition, which prevents its use for its intended purpose.

 The technical result of the invention is to improve the quality of the product by achieving a balanced composition of lump technological lime, suitable for use in the chemical, metallurgical industry, as well as in construction and agriculture.

The specified technical result is achieved by the fact that the lump of technological lime containing oxides of calcium, magnesium, iron, aluminum and silicon dioxide, according to the invention, contains components in the following ratio, wt.%:
Magnesium Oxide - 2.5-3.5
Silica - 1.0-2.5
The sum of iron and aluminum oxides - 1.0-1.5
Calcium Oxide - Else
the density of lime is 2.6-2.8 g / cm ³ .

The claimed technical solution meets the conditions of patentability "Novelty", "Inventive step" and "Industrial applicability", since the combination of features: the presence of oxides of calcium, magnesium, iron, aluminum and silicon dioxide, and, according to the invention, the content of the components should be in the following ratio, wt.%:
Magnesium Oxide - 2.5-3.5
Silica - 1.0-2.5
The sum of iron and aluminum oxides - 1.0-1.5
Calcium Oxide - Else
the density of lime is 2.6-2.8 g / cm ³ , - provides an unobvious result - improving the quality of the finished product by balancing the composition of the lump of technological lime, suitable for use in the chemical, metallurgical industry, as well as in construction and rural the farm.

 Lime is a product of calcination of natural calcium carbonates. Lump technological lime is a separate piece up to 10 mm in size with a small amount of dust fraction.

The melting point of lime is 2570 ^o C, lime interacts with water with the release of a large amount of heat, passing into slaked lime by the reaction:
CaO + H ₂ O = Ca (OH) ₂ + 65.3 kJ / mol.

By calcining Ca (OH) ₂ , quicklime CaO is again obtained.

 Slaked and quicklime absorb carbon dioxide from the medium, especially in the presence of moisture.

The technological process of lime production consists of the following stages:
charge preparation;
loading the charge into the furnace;
limestone firing;
transportation of lime to the warehouse;
lime crushing (if necessary, at the request of consumers).

 Preliminarily crushing limestone to fractions with a particle size of 40-150 mm Then the prepared limestone is loaded into the mine.

 The firing process takes place in a shaft calcareous kiln operating on the counterflow principle.

 A shaft furnace is a shaft mounted vertically on a foundation, equipped in the upper part with a device for loading source material, and in the lower part with a mechanism for unloading products.

 Limestone moving in the mine from top to bottom passes successively three technological zones: a heating zone 7 m high, a calcination zone 7.5 m high, and a cooling zone 3.5 m high.

In the heating zone, limestone is heated from ambient temperature to 800-900 ^o C due to the heat of the gaseous products moving from the burning zone. In the actual firing zone, natural gas is burned and limestone decomposes into lime, carbon dioxide at a temperature of 900-1200 ^o C.

Температуру в зоне обжига поддерживают за счет сжигания природного газа, который поступает в печь через пять газовых балок, расположенных на одном уровне.

The temperature in the firing zone is maintained by burning natural gas, which enters the furnace through five gas beams located at the same level.

In the cooling zone, the temperature of the lime is reduced by moving upward cold air to 40-70 ^o C.

To implement the method, a furnace with a capacity of 150 tons / day is used with a useful mine capacity of 214 m ³ . The cross section of the mine is slit-like.

 The furnace loading device consists of a skip hoist with an electric winch, a hopper with a lid and two leaks. The preset charge level of the charge is supported by a radioactive level indicator interlocked with the loading mechanism.

 Unloading of lime from the furnace is performed by the unloading mechanism of continuous action of a bosom design. The amount of unloading is regulated using the side of the crank and changing the number of strokes of the eyeglass case by the variator.

 Natural gas at a pressure of 2-45 kPa (0.02-0.45 bar) is fed into the furnace with a passage through a narrowing device for measuring flow. Next, the gas is distributed over the beams with simultaneous pressure control.

 Combustion air is supplied to the lower part of the furnace under the beams due to the vacuum in the furnace created by the smoke exhaust. The furnace gas from the furnace is removed from the furnace by a smoke exhauster.

 Limestone is loaded into a hopper, from where it is fed to a screen with a feeder and a conveyor belt. Fractions less than 40 mm in flow are diverted to the waste bin.

 Limestone fractions of 40-150 mm are sent to the hoppers of skip hoists and fed into the hopper of the furnace loading device. Then the limestone enters the furnace, where it moves from top to bottom due to continuous or discontinuous unloading of lime, passing successively three zones: the heating zone, the actual firing zone and the cooling zone. From the cooling zone, lime is directed through a divider to the unloading mechanism, and then to the lime hopper located in the lower part of the furnace. From the hopper as it is filled, lime is periodically fed by a feeder to the conveyor belt and then to the finished product hopper.

 If necessary (at the request of consumers), the finished lime is sent to a jaw crusher, then to a hammer mill and then downstream to a pneumatic pump transporting crushed lime to a storage hopper.

 Ready-made lump technological lime in terms of dry matter contains a mass fraction of the sum of active calcium and magnesium oxides calculated on calcium oxide of at least 70-80%, the fraction content of less than 10 mm is not less than 90%, while the lime slaking time is not more than 15 -20 minutes.

 Proposed in accordance with the present invention, the composition of lump technological lime provides an increase in the quality of the product by achieving its balance, which, in turn, makes lime suitable for use in the chemical, metallurgical industry, as well as in construction and agriculture.

Claims (1)

Process lump lime containing oxides of calcium, magnesium, iron, aluminum and silicon dioxide, characterized in that it contains components in the following ratio, wt.%:
Magnesium Oxide - 2.5 - 3.5
Silica - 1.0 - 2.5
The sum of iron and aluminum oxides is 1.0 - 1.5
Calcium Oxide - Else
the density of lime is 2.6 - 2.8 g / cm ³ .