Stoping

The Firstenbau is a mining method that is applied in mining at steep upward deposits. The Firstenbau is an important mining method for steeply dipping coal seams and vein deposits. The Firstenbau is so called because in this mining method, the degradation of the hanging wall of the basic line advancing toward the top. He is one of the removal procedure with offset.

Basic information on the process

When Firstenbau starts to degrade stepwise from bottom to top. The degradation always runs with this method on the ridges along. The overburden is used as an offset to fill the mined path and as sole for the further degradation. In order to reduce a steep angle of the deposit by this method, two parallel ascended routes are created initially above the other. For this purpose, initially created by the main haulage level of over- hoes. Is from the About Sculpting the second route, the so-called first line, ascended. The part of the deposit, which remains between the two soles is called limbo. The thickness of the float, depending on the strength of between 50 centimeters and a few meters. Both sections are connected by a so-called intermediate shaft. The degradation of Erzganges takes place only in the upper levels of the deposit, the lower sole is only used for production of the ores uphole.

The reduction can be performed on one or two leaves. The design is dependent on whether one starts the degradation to one or both sides of the over sculpting. In the single-wing design will be built until the next sculpting. In the two- bladed design, the workings of two neighboring About hewing encounter. In fissured rock masses and for narrow aisles or stratification of the country rock, the two-leaf design is inappropriate. The degradation may begin only when you have driven under the bauwürdige warehouse with a route. One distinguishes the Firstenbau different methods, these are the simple Firstenbau, the Seitenfirstenbau, the Firstenstoßbau and Firstenstoßbau with magazine storage (magazine degradation).

Easy Firstenbau

This method was the dominant degradation process on steep veins with low to medium-depth before using the machine drilling. The degradation is started from the lowest distance and applied single or double. At the two-leaf method, a route surge is occupied from the middle of the construction phase on both sides simultaneously. The double-leaf degradation is the ore mining the rule. This process results in the extraction of larger Erzmittel a good operating concentration. The single-leaf process is reduced only by one or the other side. If a surge propelled enough, then the second and then third and then the other shocks is driven. The degraded route is separated by the advance of degradation by means of a Kastenzimmerung to the base line. This Kastenzimmerung serves as a support for the mountain misalignment. The ore is transported away via so-called conveyor rollers, particularly pure pieces of ore are collected separately and transported away separately. The accumulating mountains be installed again if possible on the spot as an offset. The work per first impact is made ​​during a shift from one to two tusks. Due to the height of the drilling is partially effected by small stages, which consist of fixed transversely beaten spreading. Some of the tusks are also directly on the offset or on trips.

Seitenfirstenbau

The Seitenfirstenbau is suitable for reservoirs with thicknesses from three to ten meters. In deposits where the gears are more powerful than three meters, and where the host rock is not sufficiently stable, the simple Firstenbau be carried out no longer without major difficulties. For these deposits in the Seitenfirstenbau is applied. In this dismantling method, the vein, depending on the thickness, is divided into two or three stripes. Here the vein from the footwall, starting initially degraded by a about 2.5 meters thick strip. Subsequently, the next strip is removed. The strip is, however, only attacked when the first strip is offset sufficiently. The main transport routes are located in this method usually in the footwall. From the main conveyor lines short crosscuts will be driven up to the aisles. There are conveyor rollers at the ends of the aisles.

Firstenstoßbau

This mining method is a special type of the first building. The Firstenstoßbau is mainly applied in tough, steeply dipping deposits with stand solid country rock. This degradation process was over a long time the classical method for steeply dipping veins with solid usable mineral. The leftover rock to be a little firmly in this process. The technique is often operated in veins or seams with over 44 Gon incident. In principle, the Firstenstoßbau is a Firstenbau, in which only one shock is taken in Verhieb. Thereby, it is possible to selectively reduce the formation. So you can for example be low-grade ore mining and Erzteile are the only degrade the high-grade ore portions.

To vorzurichten the deposit, the transition is first drive in its entire thickness. About hoes are then created to the next higher floor at intervals of 60 to 200 meters. For the conveyance of the ore after rolling holes are created to the bottom line. The reduction can also be done here -leaf or double-leaf. Each First shock is individually propelled with a length of up to 200 meters extension. To create the necessary Drilling blast holes are used in today's mining industry. The working direction takes place from the bottom up. The incoming extracted mineral is transported away over the rolling holes. In order to have an adequate work surface, the lower excavated area is filled with offset. The upper floor is used for pre- promotion of the offset. As soon as the first shock advances, the basic line is displaced and laid the conveyor path up the mountain misalignment. For example, reducing down progresses upwards.

Firstenstoßbau with magazine storage (magazine degradation)

In ore mining on steeply dipping vein deposits comes as a decomposition variant also an upward guided Firstenstoßbau with magazine storage of crude ore is used, which is sometimes also shortened as " Magazine reduction" or " Magazinbau " within the meaning of " degradation with scheduled magazining the muck " means. The magazine degradation is usually used when the vein of several narrow slack side is (thus no single more powerful gear), so that a selective recovery is not worthwhile. Here, the host rock must be stable because of the degradation for a certain time is empty. In the obtained aggregate is stored in this method in the mining area. It serves the working miners as a stand and work surface.

Prerequisite for this procedure is a deposit with an incidence of at least 60 Gon. In reservoirs with a lower incidence can not be applied the procedure, since the incoming recovered ore no longer slips on the footwall. As funding for the loose debris gravity is utilized. Since the loose ore due to the bulk number one up to 80 percent larger space than the compact ore body, must be deducted from the memory during the degradation regularly ore and carried away. The deducted amount may be up to 40 percent of the memory contents. In this case, no cavities may occur in the remaining memory in the heap, as working on the pile miners would otherwise be endangered. The miners may not be on the heap during the trigger. For driving experiences and weathering over hoes be created. In order to remove the incoming recovered ore, are created in the sole area of the memory funnel with a box-shaped closure. These funnels have with each other at a distance of four to six meters. On Roll holes can be dispensed with entirely.

Such degradation process was operated for example, since 1938 until the operation closed in 1990, in the tin mine " Sauberg " in honor Friedersdorf in the Saxon Erzgebirge. Degradation and Verhiebsrichtung are here the same, that is, the vein is mined in slices of a deep sole for higher sole ( degradation towards floating, Verhiebrichtung stroking ). The device of a magazine mining block is activated by a tailgate tailgating ( eg 3 bed) and a head section ( eg 2nd floor ) and two limiting About sculpting. The thus resulting reduction block is shown in the following figure. After the first disc was blown up over the tailgate down ( Firstedrücken ), is made a working platform on the entire mining length of rails and timbers. In addition Erzabzugsrollen be installed at a distance of about 2 m. During the demolition phase, the losgesprengte ore remains in the degradation and only the resultant due to the loosening More volume is drawn through the rollers on the base line in Hunte. The slice-wise degradation takes up to 5 m below the upper sole, so that the navigability of the head distance is maintained. In the resulting mountain fortress high offset fractures are created at a distance of 15 m. Now we can be " collated " ore on the basic line in Hunte be deducted. The empty cavity loss is then added over the offsets high fractions with waste rock again.

Offset

When Firstenbau the offset plays a big role, so he has to be introduced as quickly as updated as possible. So the offset is primarily used as a support surface for the workers. About the offset, the driving experiences and the promotion to the rolling holes takes place. The offset is tilted from the top floor by over breaks in the working space. If the degradation incurred is not enough offset mountains, the offset underground must be produced in mountain mills or be conveyed forward by above ground. For deposits with so-called poor ore miner leaves in the lower base line often a one to two meter wide corridor as a stronghold standing. This program is intended to accommodate the mountain misalignment.