c.c.s. Karimova L.М., d.t.s. Zhumashev K.Zh., Kairalapov Y.Т.

Chemical and metallurgical Institute, Kazakhstan

DEFINITION of Static strength of granules of the quick-and-dirty copper concentrate OFF-BALANCE ore OF Annensk deposit

A necessary condition for the preparation of copper raw materials for firing is a raw material granulation. At the same time is very important to obtain granules, the strength characteristics that can withstand the stresses of transportation and congestion, as well as the processing in the kiln.

Study were pellets obtained from crude flotation concentrate with a particle size of the class -0,074 mm (yield 60,3%) with chemical composition (%): Cu –4,3; S –3,49; Fe–3,18; CaO – 3,05; Na₂O – 1,52; K₂O – 1,20. As a binder used in a mixture of a solution of lignosulphonate (sulphite-alcohol vinasse ρ = 1,04 g/cm³) and sulfuric acid 10%. The concentrate was subjected to pelletizing enlarged-laboratory granulator bowl with a diameter of 1,2 m, depth 15 cm and applying the binder spray. Fraction of granules need to sift sieve size class -10+7 mm (d_mean= 8,5 mm). The drying of the granules was performed on a lattice, which is fed by the hot air to the desired temperature.

Bulk density of granules γ for raw and dried at 100 ⁰C was 1016,0 and 875,2 kg/m³, respectively.

To determine the yield of whole grains in each independent experiment by fixing the load of 20 pellets were collected. Static strength, it is the way of whole grains, calculated from the probability formula energo-stahastic strength [1]. The obtained results of static strength for wet and dried granules are shown in the table. The adequacy of the experimental and calculated dependencies determined by the correlation coefficient R and its significance t_R>2.

Statistical evaluation of reproducibility of experimental data from two parallel experiments tested by the criterion of Cochran who was to be met for raw and dried grains К=0,3913<0,7800, К=0,4<0,8142 respectively.

Table – Results of experiments to determine the characteristics of an effective surface tension ρ_s, N/m, or the energy of the fracture surface, J/m², and static strength of wet and dried granules Р_s (f)

G, kg	Raw granules
	mean ()		ρs(2)		Рs(4)
0,7	0,85	655,9608	694,407	0,85	0,8909
0,8	0,825	728,8926	737,348	0,825	0,8357
1,0	0,775	869,3695	823,23	0,775	0,7022
1,250	0,625	981,3493	930,5825	0,625	0,5239
1,300	0,5	956,613	952,053	0,5	0,4900
1,500	0,25	983,3599	1037,935	0,25	0,3669
G, kg	The dried granules
	mean ()		ρs(3)		Рs (5)
1,580	0,95	1794,365	1767,796	0,95	0,9454
1,880	0,875	1820,362	1846,156	0,875	0,8845
2,280	0,75	1942,584	1950,636	0,75	0,7553
3,385	0,275	2245,617	2239,262	0,275	0,2689
3,585	0,2	2292,489	2291,502	0,2	0,1991

To determine the surface tension under the influence of static load using the formula [1]

, (1)

introduced the average values (from table) in fractions of unity. The results are shown in the table.

As the power load using the load of mass 0,7-3,585 kg, as a consequence of its physical impact is determined by the

As the table shows the effective surface tension increases regularly from raw grain (67-100 N/m) to dry (182-233 N/m).

According to the results table (G –) and construct the dependence we obtain the equations for the effective surface tension for wet and dried granules

, R=0,9057, (2)

, R=0,9933. (3)

Substituting equation (2), (3) for wet and dried granules in the model (1), we estimated probabilistic model of the static strength of wet and dried granules:

, R=0,6825, t_R=2,555>2, (4)

, R=0,8779, t_R=6,631>2. (5)

The results obtained by the static strength (4), (5) are presented in the table.

The equation for the static load can be expressed in terms of weight of the layer, since this type of load in an industrial environment is the principal (in bins, piles of drying, roasting and smelting furnaces). This load is taken into account in the approximation of ordinary packaging layer over the height and bulk density [1, p.43]

, (6)

where h_l – bed height, m, – the applied force, γ – bulk density of granules, kg/m³; – acceleration of gravity equal to 9,82 m/s².

Substitute equation (6) at (4), (5) for wet and dry beads, respectively, based on the known numerical quantities (γ, g) we estimated a model for preservation of grains under static load in the bunkers

, (7)

. (8)

Overall, the results to determine the static strength of pellets of crude copper concentrate showed the possibility of obtaining adequate dependence of the effective surface tension for both raw and dried to pellets, a fixed-breaking load with the establishment of statistical evaluation of reproducibility of experimental data on the criterion of Cochran on the output of whole grains. According to the results of experiments on the static strength of pellets effective surface tension increases regularly from raw grain (694-1037 N/m) to dry (1767-2291 N/m).

To ensure the safety of granules in the average of at least 80% of the allowable height of the layer to the average diameter of granules, for green pellets is 0,4 meters, and dried to less than 1 meter. Therefore, the layer height when filling in different silos and storage tanks shall not exceed the above quantities.

Literature:

1 Malyshev VP, Teleshev KD, Nurmagambetova AM Degradability and safety of conglomerates. - Almaty: SIC «Ғylym», 2003 .- 336 р.