**2. Post WWI reconstruction and industrialization**

After a kaleidoscopic change of ruling powers, Soviet regime was established in Kryvyi Rih region by the beginning of 1920. Iron ore was essential for reconstruction of industry, so local authorities were subordinated directly to Kharkiv, the first capital of the Ukrainian Soviet Republic. Initially, within the Kryvyi Rih deposit the martial law was imposed, but such measure was not successful and therefore it was decided to return to economic management instruments.

Reconstruction took place in very difficult conditions: famine, ruin, lack of materials, and shortage of workers. Initially, only seven mines were brought into operation. In 1927 as much as 3.5 Mt. of iron ore was mined being just 56% from 1913 level.

Since 1927 the new mining technologies have been introduced replacing the widely used cut and fill stoping method. In 1928 the first "Bucyrus" excavators were supplied from the USA along with 12 scraper winches, 7 conveyers and hammer drills of various manufacturers. The iron ore output in 1930 reached 9.78 Mt., 77% of which was produced by underground mining. Fifteen new mines equipped with an up-to-date machinery were built during the First Five-Year Plan period (1928-1932). Further mechanization of mining operations resulted in drastic increase in labor productivity and by 1940 the annual output reached 19 Mt. [4].

The mining was ceased by August 8th, 1941 - few days before Kryvyi Rih was occupied during World War II. To prevent usage of mines by the invaders, most of the equipment was transported to the mining enterprises of Ural. Units weighting over 100 t were blasted. Most of miners were also evacuated. However, more than 16 Mt. of iron ore was left in stocks.

Reconstruction of mining enterprises during German occupation was sluggish, focused mostly on nearby Nikopol manganese ore deposit being essential for the manufacture of advanced steel grades, whereas Kryvyi Rih with its iron ore stock and a huge amount of equipment turned into scrap was used as auxiliary source of iron charge in steelmaking. Demand for iron ore was hindered by slow reconstruction of coal mines in Donetsk deposit and of steelmaking enterprises on the occupied area, destroyed before the Soviet Army retreat. As a result, iron ore mining did not began until the end of 1942 and extraction of high-grade ore was started only in May 1943.

In June 1942, the removal of ore from the stock began, resulting in usage of 347 kt by the end of the year. In addition to this, from April to September 1943 about 385 kt of ore was mined. As the whole, during the period of occupation 1.78 Mt. of iron ore was taken, out of which 1.4 Mt. from the stocks [5].

In November 1943, anticipating Soviet Army's offensive, the invaders destroyed equipment, transport facilities and workshops of almost all reconstructed enterprises. As the result, out of 77 producing and servicing shafts, 54 shaft mouths were exploded or destroyed completely to the depth from 6 to 15 m. So, within 30 months the mines and the equipment have been destroyed twice.
