Using the available analytical methods, including the determination of chemical composition using wavelength-dispersive X-ray

fluorescent spectroscopy technique and phase composition determined using X-ray diffraction, microstructural observations in a highresolution

scanning microscope equipped with an X-ray microanalysis system as well as determination of characteristic softening and

sintering temperatures using high-temperature microscope, the properties of particular chromite sands were defined. For the study has been

typed reference sand with chemical properties, physical and thermal, treated as standard, and the sands of the regeneration process and the

grinding process. Using these kinds of sand in foundries resulted in the occurrence of the phenomenon of the molding mass sintering.

Impurities were identified and causes of sintering of a moulding sand based on chromite sand were characterized. Next, research methods

enabling a quick evaluation of chromite sand suitability for use in the preparation of moulding sands were selected.

The goal of this article is to application of non-silica sands based on alumininosilicates as an alternative of traditionally used chromite sand for alloyed steel and iron castings. Basic parameters as bulk density, pH value of water suspension, refractoriness, grain shape of the testing sands were evaluated. Also mechanical properties of furan no-bake moulding mixtures with testing sand were determined. Finally, the influence of non-silica sand on casting quality was evaluated via semi-scale under normal casting production for sand characterization Optimization of production process and production costs were described.

In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is

presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within

100 to 1200 °C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared

with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation

of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand

grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The

observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in

internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at

elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular

particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of

chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand

and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.

In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is

presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within

100 to 1200 °C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared

with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation

of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand

grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The

observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in

internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at

elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular

particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of

chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand

and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.

Chromium ore is treated as an important strategic raw material. It is used by many branches of the industry. The most important applications are metallurgical, refractory and chemical. Unfortunately, no chromium ore deposits have been found in Poland until now, with the exception of two chromium ore sites described in the Lower Silesia region. These concentrations are formed by chromitite, which is rock consisting mainly of chromian spinel. They are localized within so called Sudetic Ophiolite rocks along the edge of the Góry Sowie Massif. They form typical podiform deposits, which are characterized by the high Al content of the rock. The first locality, near Tąpadła village (the Gogołów-Jordanów Massif), is better known. The ore was exploited here at the turn of the19th century and at the beginning of the 20th century. According to the literature, 3500 tons of the ore was obtained - all the resources at this location. The second locality, situated at the Braszowice-Brzeźnica Massif, was never studied and described properly, falling into obscurity since the 19th century. During the field work at the Braszowice-Brzeźnica Massif, the author has found numerous chromium ore fragments among the debris. The rising prices of chromium on the world's markets suggest that it is reasonable to study the ore quality and overall resource potential of this deposit. The preliminary studies have shown that chromitities from Braszowice are typical ores of the podiform variety, the majority texturally massive and nodular. The chemical analyses of the primary chromianspinels grains revealed that they could be treated as refractory chromite (38% wt. of Cr2O3, lower than 30% wt. of Al2O3, and Cr/Fe ratio about 3:1). However, the metamorphic processes modified the primary chemical composition of the studied ore. They caused enrichment in Fe and Cr, and a decrease in Al in comparison to the primary ore. Moreover, the whole rock chemical analyses revealed that the content of the main elements is insufficient to use the ore without enrichment processes. Furthermore, the size and number of the potential ore bodies are presumably small. Consequently, both the chemical composition and the resources of the chromium ores from the Braszowice–Brzeźnica Massif are insufficient to allow for profitable exploitation, despite the high price of chromium.

The paper presents an original method of measuring the actual chromite content in the circulating moulding sand of foundry. This type of

material is applied for production of moulds. This is the case of foundry which most frequently perform heavy casting in which for the

construction of chemical hardening mould is used, both the quartz sand and chromite sand. After the dry reclamation of used moulding

sand, both types of sands are mixed in various ratios resulting that in reclaimed sand silos, the layers of varying content of chromite in

mixture are observed. For chromite recuperation from the circulating moulding sand there are applied the appropriate installations

equipped with separate elements generating locally strong magnetic field. The knowledge of the current ratio of chromite and quartz sand

allows to optimize the settings of installation and control of the separation efficiency. The arduous and time-consuming method of

determining the content of chromite using bromoform liquid requires operational powers and precautions during using this toxic liquid.

It was developed and tested the new, uncomplicated gravimetric laboratory method using powerful permanent magnets (neodymium).

The method is used in the production conditions of casting for current inspection of chromite quantity in used sand in reclamation plant.