Lime burned magnesian rocks

Lime the knitting material received by roasting and the subsequent processing of limestone, chalk, etc. limy and magnesian rocks. Pure lime - a colourless product, is badly dissolved in water (about 0,1% at 20 C), density about 3,4 g/cm3.

Depending on a chemical composition and conditions of curing lime is subdivided on air, hardening in air and dry conditions, and hydraulic which hardens on air and in water.

Air lime is received roasting mainly of limestone with the small content of clay (to 8%) at 1100-1300 With in the mine or rotating calcination furnaces. At the same time the carbonates which are a part of breed decay, for example: SASO3 SAO + CO2. Depending on contents in breed of MgO distinguish the following types of lime: calcic (contains up to 5% on the mass of MgO), magnesian (5-20%) and dolomitic (20-40%).

Depending on a way of processing of the burned product receive not extinguished lump (kipelka), not extinguished ground and extinguished (hydrate) lime, or a pushonka, and also limy dough. The first represents mix of the pieces of various size which are formed after a rough grinding of a product of roasting. On a chemical composition it consists of SAO and MgO with small impurity of SASO3 which did not decay when roasting, and also of silicates, aluminates and ferrat of calcium. Not extinguished ground lime - a product of such grinding of lump lime. Extinguished lime - the high-disperse dry powder received by interaction of lump or ground not extinguished lime with a small amount of water or couple (clearing) consists mainly, of Sa (IT) 2 and Mg(OН)2 with SASO3 impurity. When clearing lime with a large amount of water the plastic pasty weight, so-called limy dough is formed.

Activity of air lime as the knitting material is defined by the general content of oxides of calcium and magnesium. The calcic lime containing 93-97% of oxides possesses the greatest activity. High-quality grades of lime ("fat lime") are characterized by a big release of the limy test (more than 3,5 l on 1 kg of negashenny lime), than the release of the test, subjects it more plastic is higher and can accept a large amount of sand at preparation of construction solutions.

On the speed of clearing distinguish fast-extinguished (process duration no more than 8 min.), srednegasyashchuyusya (no more than 25 min.) and medlennogasyashchuyusya lime (more than 25 min.). Time from the powder mixing moment is accepted to the speed of clearing. Lime with water until achievement of the maximum temperature of mix.

The offered lime of the Global Chemicals Company LLP organization with the maintenance of SAO - 99,82%, and MgO - no more than 5% belongs to air not extinguished and calcic with high activity. This lime is available in this organization in the form of pieces and the crushed look.

Usually in enrichment hydraulic lime of low activity is used, to a t.a, the maintenance of the SAO and MgO main components is less than 50%, it contains silicon dioxide, silicates, alumina much, etc. These impurity are ballast form the additional slimes interfering the process of enrichment of sulphidic ores. Therefore use of lime of high activity much more reduces the price of process of enrichment of technogenic trudnoobogatimy ores of non-ferrous precious and rare metals. Now we will consider what role is played by lime in the course of enrichment.

If to use pure SAO to which lime of the Global Chemicals Company organization treats with the maintenance of SAO of 99,82% then extraction of copper in copper, lead in lead, zinc in zinc and pyrites in pyritic concentrates on average increases by 8-10%, in comparison with lime use by activity of 70%. At the same time the lime consumption with high activity is significantly cut. The received concentrates for removal of organic flotoreagent process sulfide of sodium (Na2S) with an expense 6-8 kg/t. Sulfide of sodium is toxic substance, besides, has an unpleasant pungent smell. Recently instead of this toxic reagent use ecologically safe product representing mix of extinguished Ca (OH) 2 lime with sulfur in certain ratios. Quality of this mix strongly depends on activity of lime, the activity of the used lime is higher, the better it is more stoutly cleared of organic flotoreagent.