CN102925676B - Novel energy-saving technology for producing pellets with fine-grained iron ore concentrates - Google Patents

Abstract

The invention discloses an energy-saving process for producing pellets from fine-grained iron concentrate. It is characterized in that it includes the following steps: feed the iron ore concentrate slurry into the concentrate thickener for concentration → ceramic filter → batching operation → strong mixer for mixing operation → disc pelletizing machine for pelletizing operation, after pelletizing The raw balls are sent to the small roller sieve for screening, after the treatment of the small roller sieve, the unqualified raw balls return to the pelletizing process to participate in the pelletizing process again, and the qualified raw balls are sent to the large roller sieve for secondary screening. The product under the roller screen returns to the pelletizing process, and the product on the large roller screen is fed into the chain grate machine. After being fed into the chain grate machine, the qualified green balls are dried and preheated by the chain grate machine, and then sent to the rotary kiln for roasting and cooling. Afterwards, it becomes a qualified pellet mineral product. Its advantages are: on the premise of ensuring the quality of pellet products, by optimizing the production process and improving the production process, energy saving and emission reduction are realized.

Description

Energy-saving Technology of Fine-grained Iron Concentrate to Produce Pellets

technical field

The invention belongs to the technical field of mineral processing, and in particular relates to an energy-saving process for producing pellets from fine-grained iron concentrates.

Background technique

With the effective implementation of the macro-control and result optimization of my country's iron and steel industry, the construction speed of the pellet plant is very rapid. At present, there are more than 50 pellet production lines with a scale of more than one million tons. Furnace charge structure, to increase iron and save coke, reduce pig iron production cost, provide the most basic conditions and the most effective technical measures. There are generally three processes for the production of pellets, namely shaft furnace, belt machine and chain grate machine-rotary kiln. At present, the pellet production process of large and medium-sized enterprises is mainly based on belt machine and chain grate machine-rotary kiln. Because the chain grate machine-rotary kiln has obvious advantages such as coal powder can be used as the basic fuel, the adaptability to raw material changes is stronger than that of the belt machine, the requirement for high-temperature materials is low, and the production cost is low, most of the newly built large and medium-sized pelletizing plants adopt this method. kind of craft. However, the chain grate machine-rotary kiln production process is not perfect. For example, the iron concentrate required for the production of pellets needs to be dried in a drying kiln to reduce the moisture content to below 9% to meet the requirements of the next mixing and pelletizing process. Converted into Each ton of pellets needs to consume about 1 kg of coal, and the wet return material produced during the pelletizing process and the broken balls and powder under the chain grate plate sieve, that is, dry bulk materials, require special crushing equipment (generally However, since the design of the wet return crushing equipment itself is not necessary, and the crushing effect of the dry return equipment has not been ideal, a lot of spare parts, electric energy and labor maintenance costs are wasted in vain.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the prior art, to provide a fine-grained iron concentrate production pellet energy saving by optimizing the production process, improving the production process, and realizing energy saving and emission reduction under the premise of ensuring the quality of the pellet product. craft.

According to the fine-grained iron concentrate production pellet energy-saving technology of the present invention, it is characterized in that: comprise the following steps:

(1) Feed the iron concentrate slurry with a concentration of 25-35%, a particle size of -200 mesh, a content of 90-95%, and a grade of 67-67.5% into the concentrate thickener for concentration, and the concentration of the concentrated slurry is 55%-65% Feed into a ceramic filter for filtration, and the moisture content of the filtered concentrate is controlled below 9%;

(2) Feed the filtered iron concentrate into the batching operation, and the batching is according to the weight ratio: iron concentrate: bentonite: dedusting ash is 1: 0.011-0.016: 0.012-0.02 and fed into the intensive mixer for mixing operation, The iron grade of the mixed material is 66-66.5%, and the water content is below 9.1%;

(3) Feed the mixed material into the disc pelletizer for pelletizing operation. After pelletizing, the moisture content of the raw pellets is 9.3%±0.2%, the drop height is 500mm, the drop strength is more than 4 times, and the compressive strength is 11N More than / ball, the average particle size is 10-13mm;

(4) After pelletizing, the raw balls are sent to a small roller screen for screening, and the upper roller gap of the small roller screen is controlled at 6-9mm, and the lower roller gap of the small roller screen is controlled at 12-16mm, and the particle size is obtained by screening. 9-16mm qualified green balls, particle size < 9mm and particle size > 16mm are unqualified green balls;

(5) After being processed by the small roller sieve, the unqualified raw pellets return to the pelletizing process to participate in pelletizing again, and the qualified raw pellets are sent to the large roller sieve, and the gap between the large roller sieves is controlled at 5-7mm for secondary screening , the product under the large roller sieve returns to the pelletizing process, and the product on the large roller sieve is fed into the chain grate machine, and the gap between the grate plates is controlled at 5-7mm;

(6) The qualified raw balls fed into the chain grate machine are dried and preheated by the chain grate machine, and then sent to the rotary kiln for roasting. After roasting, they are cooled by the ring cooler and become the final grade of 65-65.2% and the FeO content is less than 1%. Qualified pelletized mineral products.

During the drying process of the chain grate machine, the broken dry balls discharged through the gaps or gaps of the grate plate are called dry bulk materials. The dry bulk materials are discharged through the ash legs of the chain grate machine with a vibration device. The discharge time of the dry bulk materials is It should be synchronized with the feeding time of the mixed material in the pelletizing process, and the bulk material should be dried at the same time or a material stabilization control device should be fed through the belt to strictly control the amount of output minerals and then return to the pelletizing process. The amount of dry bulk material per unit time should be discharged. And the delivery volume is required to be less than 4% of the mixed material volume per unit time. the

The material stabilizing control device is composed of a mine bin, a feeder connected to the mine bin and a weighing scale arranged on the feeder.

Compared with prior art, the advantage of the present invention is:

The present invention aims at the actual production process of the chain grate machine-rotary kiln pellet production process, by optimizing the production process, using a ceramic filter to reduce the moisture content of the concentrate, canceling the original concentrate drying operation, and saving a lot of power consumption; Due to the actual situation of low efficiency and high energy consumption in the process of raw pellet crushing and dry return crushing, the original green pellet crushing and dry return crushing production links have been canceled by optimizing the parameters of the roller screen equipment and controlling the amount of dry return material reasonably and stably. , so that the production process can be further optimized. The implementation of the invention fully improves the pellet production process efficiency, stabilizes various technical indicators, and has remarkable energy-saving and emission-reducing effects.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Detailed ways

The present invention will be further described below in conjunction with drawings and embodiments.

As shown in Fig. 1, fine-grained iron concentrate of the present invention produces pellet ore energy-saving technology, it is characterized in that: comprise the following steps:

(1) Feed the iron ore concentrate pulp with a concentration of 30%, a particle size of -200 mesh, a content of 93%, and a grade of 67.3% into the concentrate thickener for concentration, and feed the concentrated pulp with a concentration of 60% into a ceramic filter for filtration. The filtered ore concentrate moisture is 8.8%;

(2) The filtered iron concentrate goes through the batching operation, and the batching is based on the weight ratio: iron concentrate: bentonite: dedusting ash is 1: 0.014: 0.015 and is fed into the intensive mixer for mixing operation. The iron grade of the mixed material is is 66.4%, and the water content is below 8.9%;

(3) Feed the mixed material into the disc pelletizer 11 for pelletizing operation. After pelletizing, the average moisture content of the raw pellets is 9.3%, the drop height is 500mm, the average drop strength is 4.5 times, and the average compressive strength is 12N / ball, the average particle size is 12.5mm;

(4) After pelletizing, the raw balls are fed into the small roller screen. The small roller screen has 21 sieve rollers. The gap between the 1-9 sieve rollers in the upper part is 7mm, the gap between the 9-10 sieve rollers is 12mm, and the bottom 10- The 21 sieve rollers have a gap of 15mm, and sieve, and sieve out qualified green balls with a particle size of 9-16mm, and unqualified green balls with a particle size of <9mm and particle size>16mm.

(5) After being processed by the small roller sieve, the unqualified particle size < 9mm and the particle size > 16mm raw pellets are returned to the disc pelletizer to participate in pelletizing again, and the qualified raw pellets are fed into the large roller sieve, and the large roller sieve is 27 The root roller and the gap between the sieve rollers are both 5.5mm. Secondary sieving is carried out to screen out two kinds of products on the sieve and under the sieve. The raw balls return to the disc pelletizer together for re-balling,

(6) After the products on the large roller screen are fed into the chain grate machine, the drying and preheating operations are completed, and two products of preheating balls and dry bulk materials are produced. The gap between the grate plates is 5.5mm, and the dry bulk materials are fed into the stable material After the control device, the dry bulk material is output after the output is controlled, and the dry bulk material is returned to the disc pelletizer together with the under-screened product sieved by the large roller sieve and the unqualified green balls sieved by the small roller sieve. For pelletizing, the preheated balls are roasted in a rotary kiln and then fed into a ring cooler. After cooling, they become qualified pellets with a final grade of 65.1% and a FeO content of 0.8%.

The average daily output of the pellet production line with an annual output of 2 million tons is calculated based on 6100 tons, the operating rate is 90.5%, the consumption of iron concentrate is 980kg/t, the consumption of bentonite is 14kg/t, and the consumption of dust removal ash is 15kg/t. The amount is 6160 tons / day. The daily output of dry bulk material is calculated as 200 tons per day, the batching amount of iron ore concentrate is set to 500t/h, the ratio of bentonite is 1.4%, and the ratio of dust removal ash is 1.5%. The amount of mixed material is calculated to be 514.5t/h, and the batching and mixing system needs to be operated for 12 hours. It is determined that the number of discharges of dry bulk materials is 12 times/day, once every 2 hours, and the hourly discharge amount is 16.7 tons, accounting for 16.7 tons of mixed materials. The proportion of material is 3.24%.

The present invention replaces the function of the original rotary drum dryer with the concentrate thickener and ceramic filter, and cancels the unqualified -9mm green balls, +16mm green balls and large rollers used for screening out by the small roller sieve. The original crushing equipment for unqualified under-screen products screened out, and by strictly controlling the amount of dry bulk materials, the defects of the original crushing equipment were solved, and the original crushing equipment for drying bulk materials was cancelled.

The present invention optimizes the entire production process, and the production operations and technical methods have more reasonable changes than before.

(1) After using the ceramic filter, the moisture content of the concentrate can reach below 8.8%, and the moisture content of the concentrate can be controlled by adjusting the ore feeding amount, feeding concentration and cleaning system of the filter, and the operating cost is much lower than other methods and processes .

(2) The wet return material produced by the subsequent screening operation of pelletizing has basically turned into powder after repeated belt transportation (with a certain drop), which has no effect on subsequent pelletizing.

(3) By strictly controlling the gap between the large and small roller screens and the gap between the grate plates of the chain grate machine, especially by strictly controlling the amount and running time of the dry bulk material returning to the pelletizing process, the proportion of dry bulk material in the mixture is controlled below 4%. , and then canceled the dry bulk crushing equipment, so that the +0.076mm~-8mm particle size content in the dry bulk material that has a greater impact on the pelletizing process can be reduced by about 20% compared with the original crushing equipment, while the -0.076mm particle size And +8mm particle size has no effect on the pelletizing process, so the improvement not only reduces the cost of the process, but also improves the quality of the process.

Claims (3)

1. a granule iron concentrate is produced the pellet energy-saving technique, it is characterized in that: comprise the following steps:

(1) the iron ore concentrate ore pulp of concentration 25-35%, granularity-200 order content 90-95%, grade 67-67.5% being fed the concentrate thickener concentrates, the ore pulp of concentration 55%-65% after concentrated feeds ceramic filter and filters, and the iron ore concentrate moisture controlled after the filtration is below 9%;

(2) iron ore concentrate after will filtering feeds batch operation, its the batching be by weight by: iron ore concentrate: wilkinite: dedusting ash is 1: 0.011-0.016: 0.012-0.02 feeds intensive mixer and carries out mixture operation, the iron grade of material is 66-66.5% after mixing, and moisture is below 9.1%;

(3) mixed material is fed balling disc and carry out the pelletizing operation, the green-ball moisture after the pelletizing is 9.3% ± 0.2%, dropping strength is more than 4 times, and ultimate compression strength is more than the 11N/ ball, and mean particle size is 10-13mm;

(4) feeding little roll screen through the green-ball after the pelletizing sieves, pony roll is sieved top sieve roller clearance control at 6-9mm, pony roll lower part of screen sieve roller clearance control is sieved out the qualified green-ball of granularity 9-16mm at 12-16mm, and granularity＜9mm and granularity＞16mm are defective green-ball;

(5) return the pelletizing operation through the underproof green-ball of granularity after the processing of pony roll sieve and again participate in pelletizing, the green-ball that granularity is qualified feeds big roll screen, its big roll screen clearance control is carried out regrading at 5-7mm, the big roll screen screen undersize returns to the pelletizing operation, the big roll screen oversize feeds chain grate machine, and its grate plate slit is controlled at 5-7mm;

(6) feed that qualified green-ball behind the chain grate machine is dry through chain grate machine, feed rotary kiln after the preheating and carry out roasting, after the roasting through becoming final grade 65-65.2%, FeO content after the central cooler cooling less than 1% qualified pellet product.

2. granule iron concentrate according to claim 1 is produced the pellet energy-saving technique, it is characterized in that: the fragmentary dry bulb of discharging by grate plate slit or other slit in the described chain grate machine drying process is called dry bulk cargo, dry bulk cargo is discharged with the grey leg of rapping apparatus by chain grate machine, the efflux time of dry bulk cargo will with pelletizing operation compound material loading time lock, dry bulk cargo will feed a steady material control device by belt simultaneously, return to the pelletizing operation after the defeated yield of strict control, the blowing amount of the dry bulk cargo of unit time and operational throughput require less than 4% of unit time compound amount.

3. granule iron concentrate according to claim 2 is produced the pellet energy-saving technique, it is characterized in that: described steady material control device is by ore storage bin, and the ore storage bin feeding machine that connects and the weighing balance that is arranged on the feeding machine forms therewith.