Nearly a decade or two ago hydraulic lime was delivered to the construction site unprepared – without subjecting to roasting. It was quenched similarly to the as the common lime and put directly into the dough, kneading bad crumbling pieces of beetles, runners, and so on. With this process the fine grain burnout largely remained intact, capable of ruining your late solution subsequently quenching.
That’s why the French method of processing lime is gaining momentum, implying division lime material into several fractions, depending on the speed and completeness of quenching the latter, though it arrives at the shelves of specialty stores in the form of powder. The prominent construction and architectural organisations, like Telling Company, widely applying hydraulic lime and lime mortar solutions, makes a choice in favour of this method, so let’s have a closer look at it.
The furnaces hydraulic lime are essentially identical to the common uses for the firing of lime. In France for quite a long time short flame furnaces with egg-shaped shafts (9 meters in height and maximum width of 3.5 m and 1.6 m diameter furnace top) have been used, arranged next to one another in the general stone casing. At the bottom of the shaft of peculiar form of the grate in the form of a conical cage of iron bars is set in the midst of which ordinary horizontal grille and prominent inland mines to a height of 1.75 m installed. Such a device is intended to increase the contact of surface with the air burned with material located in the lower part of the shaft, and thus accelerate its cooling. Side sections for unloading are not implemented, as all mine raised above the ground so that the trolley can fit under the grate and take material. Furnace top tight-fitting lid, suspended on a chain to the rocker with a counterweight, to slip the gases from the furnace wall of the latter, beneath the furnace throat, there are openings to the horizontal elections, common to a number of furnaces and conductive gases to the sucking fan.
Gas furnaces design
The newest generation of gas furnace is significantly larger in sizes. The firing temperature must always be consistent with the properties of marl; if the various layers vary in composition, such approval to the common shaft furnace is almost unattainable. In such cases, marl materials can be shattered and burnt in a mixture of all of its layers in rotary kilns. Burned pieces after leaving the oven are immediately subjected to quenching, as a rule, with warm or hot water (or alternatively in rotating iron drums). Water is used in significantly lower amounts in comparison with ordinary lime. The size of the drum is 15 m in length and 2.1 m in diameter; while the temperature therein is raised to 250 – 270° so that the damping is subjected to high pressure steam, and therefore it is quite rapid. Semi-quenched lime is served in a bucket of elevators silos – concrete high tanks of cylindrical or prismatic shape with a funnel-shaped bottom; these silos complete quenching within 1-2 weeks.