Process for calcining molybdenum ore concentrate
Technical field
The present invention relates to a kind of roasting method of concentrated molybdenum ore, the molybdenumdisulphide oxidation sweetening is formed molybdenum oxide.
Background technology
Concentrated molybdenum ore is mainly with molybdenumdisulphide (MoS
2) the form existence, standard ore deposit (Mo45%) sulfur-bearing is about about 33%.Prior art uses reverberatory furnace, multiple hearth furnace and external heating type rotary kiln etc. with the calcining molybdenum ore concentrate oxidation sweetening usually.
The reverberatory furnace investment is little, production capacity is low, but labor condition is abominable, tail gas SO
2Concentration is low, and single device day is handled concentrate 2 * 10
3Below the kg, belong to national explicit order and eliminate equipment.The multiple hearth furnace facility investment is big, adopts mechanical rake animal material, the layering temperature control, and single kiln production capacity is 20 * 10
3More than the kg, only be applicable to large-lot producer, too complicated because of device systems simultaneously, maintenance load is big, and the returning charge amount surpasses 20%, tail gas SO
2Concentration is lower than 1%.Adopt the external heating type rotary kiln to produce in the molybdenum oxide process, flame directly-fired kiln skin, the kiln body does not have firebrick lining, the furnace charge autothermal reaction is the direct heating kliner coating also, since inside and outside the gas that is heated and is corrosive form, service life of kiln body is shorter, the also as easy as rolling off a log fracture of kiln body of promptly using high temperature steel to make, and external heating type rotary kiln separate unit is handled concentrated molybdenum ore 3 * 10
3About kg, the reason of producing that can not maximize also is this.
Once adopted rotary kiln to carry out the roasting of chromium slag or vanadium slag in the prior art, in Chinese patent CN2082844U, had a detailed description.The rotary kiln that is adopted is that inner heating, slightly-inclined are placed, and burner is installed in kiln.The internal heating rotary kiln that the roasting of concentrated molybdenum ore of the present invention is used and the structure of this rotary kiln have significant difference, by auxiliary hearth is set, bring beneficial effect for the sulfur removal technology process and the product of concentrated molybdenum ore.
Summary of the invention
The present invention adopts the internally heated type rotary kiln to carry out the roasting of concentrated molybdenum ore, can overcome the numerous shortcomings that adopt reverberatory furnace, multiple hearth furnace or external heating type rotary kiln baking concentrated molybdenum ore.Can access doctor negative molybdenum oxide after the roasting.
The present invention utilizes the internally heated type rotary kiln to carry out roasting, this internally heated type rotary kiln is the speed governing rotary kiln made from general steel plate, the interior firebrick lining of building, the kiln hood place becomes vertical direction that auxiliary hearth is set with rotary kiln, and gas burner is placed in the auxiliary hearth, flame in the gas burner becomes vertical direction with rotary kiln, be positioned at 150-250mm under the kiln medullary ray, auxiliary hearth one side is provided with blue-gas generator, and coal gas imports burner, the kiln tail is installed cyclone and tail gas elution circuit, and reactions steps is as follows:
(1) concentrated molybdenum ore is sent in the internally heated type rotary kiln, promptly entered the desulfurization main reaction after going into kiln, maturing temperature is 500-580 ℃, and the residence time is 7-8 hour, and sulphur content is reduced to 1-2%, non-essential adding sweetening agent in the roasting process;
(2) take off residual sulphur in auxiliary hearth, temperature is controlled at 550-600 ℃, and the residence time is 20-50 minute, and the molybdenum oxide sulphur content reaches below 0.07%;
(3) reclaim the product molybdenum oxide, and return imitation frosted glass by cyclone and the collection of tail gas elution circuit.
When wherein coal gas imported burner, one time wind was adjusted the coal gas amount, and secondary air is adjusted oxygen-supplying amount.
Can directly utilize coal or oil to be fuel.
Furnace charge is 20-50 minute in the auxiliary hearth residence time, is preferably half an hour.
The concentrated molybdenum ore of desulfurization difficulty is added sweetening agent bicarbonate of ammonia when the roasting, and concentration is 1-3%.
This technology invention technical essential is: 1, auxiliary hearth is set takes off residual sulphur; 2, coal gasification combustion, a wind temperature control.Secondary air control excess air; 3, add sweetening agent and promote desulfurization.
Description of drawings
The internally heated type rotary kiln synoptic diagram that Fig. 1 uses for process for calcining molybdenum ore concentrate of the present invention.Wherein 1 is rotary kiln, and 2 is auxiliary hearth, and 3 is blue-gas generator, and 4 is the tail gas elution circuit, and 5 is charging machine.
Embodiment
Embodiment 1
Concentrated molybdenum ore is reinforced from kiln tail charging machine 5, and concentrate promptly enters the desulfurization main reaction after going into kiln.Concentrated molybdenum ore is evenly reinforced, adopts φ 1.6 * 21m rotary kiln, per hour reinforced 420kg, and maturing temperature is 550 ℃, and kiln residence time is 7.5 hours, and sulphur content reduces to 1.4% from about 30%.
Take off the residual sulphur stage and finish at auxiliary hearth, temperature is controlled at 580 ℃, to reduce molybdenum distillation loss.Furnace charge is 35 minutes in the secondary stove residence time.Because secondary stove has enough areas, furnace charge takes off the residual sulphur time at auxiliary hearth and can prolong as required.The imitation frosted glass amount of returning that collect kiln tailspin wind dust-precipitator and gravity dirt chamber accounts for total stuff amount below 10%, tail gas SO
2Concentration is 1%, utilizes the combustion of sulfur method to measure that sulphur content is 0.05% in the product molybdenum oxide.
Single kiln concentrate treatment capacity is 7 * 10
3More than the kg, molybdenum oxide output 5-6 * 10
3Kg.Flue gas enters eluting column and reclaims remaining molybdenum concentrate dust and gaseous state MoO after dry dust collection
3Comprise and do wet gathering dust, the molybdenum roasting rate of recovery reaches more than 98.5%.
Embodiment 2
Concentrated molybdenum ore is reinforced from kiln tail charging machine 5, and concentrate promptly enters the desulfurization main reaction after going into kiln.Concentrated molybdenum ore is evenly reinforced, adopts φ 1.6 * 21m rotary kiln, per hour reinforced 380kg, and maturing temperature is 560 ℃, and kiln residence time is 7 hours, and sulphur content reduces to 1.1% from about 30%.
Take off the residual sulphur stage and finish at auxiliary hearth, temperature is controlled at 590 ℃, to reduce molybdenum distillation loss.Furnace charge is 30 minutes in the auxiliary hearth residence time.Adding sweetening agent concentration is 1-3% bicarbonate of ammonia.The returning charge amount that collect kiln tailspin wind dust-precipitator and gravity dirt chamber accounts for total stuff amount below 10%, tail gas SO
2Concentration is 0.9%.Utilize the combustion of sulfur method to measure that sulphur content is 0.04% in the product molybdenum oxide.
Compare with traditional molybdenum roasting technique, the major advantage of this technology invention is:
Sequence number | | Reverberatory furnace | Many thoraxes kiln | The external heating type rotary kiln | The internal heating type rotary kiln | Remarks |
1
| Amount of investment | Minimum | Maximum | Bigger | Less | |
2
| Single stove production capacity, T |
2
|
20
|
3-4
|
7-8
| In molybdenum concntrate |
3
| Return the burning rate, % |
<5
|
>20
|
>20
|
<10
| Comprise gather dust material and defective material |
4
| Applicability | Small-sized | Large-scale | Medium-sized | Medium-sized | |
5
| Molybdenum recovery, % |
97-98
|
98-99
|
>98.5
|
>98.5
| |
6
| Burning consumes | Bigger | Minimum | Maximum | Less | |