EFFECT OF MILLING METHOD
ON CHROMITE SURFACE COMPOSITION AND SINTERING
I. D. Kashcheev
and K. G. Zemlyanoi
Translated from Novye Ogneupory, No. 12, pp. 18 – 23, December, 2014.
Original article submitted August 18, 2014.
Milling of chromite concentrate is studied in equipment with different milling methods and energy intensity. It
is established that milling gives rise to a different chromite fine particle surface structure, different nature and
amount of microdeformation within particles, and different chemical activity. Milling has almost no effect on
material phase composition. Within a layer more than 50 Å there is magnesium silicate entirely screening
chromium spinelid at a chromite particle surface subjected to fine milling.
Keywords: chromite, energy intensity, fine milling, microdeformation, coherent scattering region, surface
The state and composition of a surface has a marked ef-
fect not only on physicochemical and production properties
of oxide materials during manufacture of molded and
unmolded refractories, but also on their operating properties
in various heating units. Such processes as wetting, spread-
ing, impregnation, and others, arising at a material – melt
contact mainly depend on surface condition, its chemical
composition, and capacity of atoms for reaction with melt.
The surface of actual solids is rarely uniform. Two con
ditions are typical for these surfaces, i.e., inhomogeneity
with respect to chemical composition, and different structure
. With respect to natural chromite it combines both variet
ies: with respect to chemical composition it is complex far
from stoichiometric compounds, and for structure it is com
plicated by different mineral phases. Differences may be
very large, particularly for crystal phases, having a small de
gree of symmetry within which therefore anisotropic proper
ties differ particularly distinctly.
Previously  the effect has been established for milling
methods of melted Al
, MgO, and MgAl
and the effect of surface composition on structure formation.
In this work chromite concentrate produced by OAO
TNK KazKhrom grade KhK-2, answering the specifications
of TU 0741-002-51824642–2003, is used. The phase compo
sition of concentrate, wt.%: chromium spinelid 70 – 77, ser
pentine 15 – 20, forsterite 2 – 5, amorphous phase 2 – 5. The
concentrate is produced in the form of granular product of
The grain size composition of finely milled powder was
determined by photo sedimentation in a Sed-Auto-Graph-02
laser sedimentograph from Shimadzu according to GOST
The true density of powder was determined by a
pycnometric method according to GOST 2211 and specific
surface was determined by a chromatographic method by
thermal desorption of inert argon gas (BET method) accord
ing to GOST 23401 and proposed in .
Material phase composition was determined in a
MiniFlex 300/600 x-ray diffractometer (Rigaku Co., Japan)
-radiation. The recording rate was 2 deg/min, an
ode – cathode voltage 40 kV, anode current 15 mA, record
ing range 3 – 90° with a step of 0.01°. In order to intensify
phases and determine crystal lattice parameters PDXL
(Rigaku Co.) software and a JCPDS (Joint Committee on
Powder Diffraction Standards, 7-th edition, 2001) card index
The value of minimum dislocation density r,cm
evaluated in material from a relationship 
where D is coherent scattering region (CSR) size, cm.
or from the quadratic dependence of dislocation density
r of true expansion of line b from a relationship 
r = Ab
Refractories and Industrial Ceramics Vol. 55, No. 6, March, 2015
1083-4877/15/05506-0549 © 2015 Springer Science+Business Media New York
FGAOU VPO Ural Federal University, Ekaterinburg, Russia.