Pellets Plant

Pellets Plant Production Process (Huasco Valley)

The Huasco pellets plant is located 5 km from the port of Huasco and 700 km to the north of Santiago. Its start-up was in late 1978, with a nominal annual capacity of 3,500,000 tons of pellet product.

 

The mineral processed comes from Los Colorados mines where it is subjected to various stages of grinding and dry magnetic concentration, from which the product called pre-concentrates is obtained. This product is transported by rail to the pellets plant where it is stored and homogenized in reception yards. From here it is sent selectively to the crushing and wet magnetic concentration processes in order to reduce particles to a size suitable for eliminating the impurities and obtaining a specific surface suitable for pelletization.

 

The magnetic concentrate is filtered and later pelletized in discs, blended with a mixture of additives that act as agglomerants in the pelletization and scorification process in the later stage of thermal hardening.

 

The thermal treatment of the green pellets that have been classified to a suitable size begins in a straight grill of four zones where they are dried and pre-heated to be fed into the rotating furnace where they are heated to a temperature of 1,300 °C. This confers the final characteristics of strength, chemical and physical-metallurgical properties necessary for use in blast furnaces, Corex process or direct-reduction modules.

 

From leaving the plant, continuous improvements in the whole process have enabled an increase in production, reduced specific consumption and a diversification of products, reaching an annual production of four million tons of pellets for blast furnaces and direct reduction, and a million tons of pellet feed.

 

Description of the Production Process by Areas

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transportation of Pre-concentrates

 

The pre-concentrates produced in Los Colorados mine are transported by rail to the pellets plant, a distance of over 109 kilometers.

 

 

 

 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Storage of Pre-concentrates

 

The pre-concentrates from the mine are stored and homogenized in a yard with a total capacity of 500,000 tons. According to their quality and destination, the pre-concentrates are stockpiled in various piles of defined qualities for their later processing.

 

 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wet Crushing and Classification

 

The pre-concentrates are taken from the stockpiles to the crushing stage which is currently composed of three processing lines. Each line has a ball crusher of 16.5 by 37.5 feet with a 6,000 HP motor, in closed circuit with a battery of 6 hydrocyclones.

 

The iron ore is reduced in size and classified 80% below 44 micrones.

 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Magnetic Concentration

 

The concentrator has a combination of batteries of 36” diameter and 750 Gauss and others of 48” diameter and 1,000 Gauss, making up the stages of primary concentration and of revision, generating a magnetic concentrate that is transferred to the following filtering stage, and the tailings sent to a condenser where the water is recovered and the small flow is finally discharged in an underwater pipeline.

 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Filtering

 

The concentrates are subjected to condensing and then transferred to agitator tanks where they are homogenized and then filtered in disc filters where the pellet feed is obtained and the cake which is fed to the balling process to produce the pellet product.

 

 

 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Balling

 

The filtered cake is mixed with an additive in an amount according to the type of pellet to be produced and the mix is fed and transformed into green pellets in the pelletizer discs, passing then to roller sifters where are they are selected according to their size.

 

 

 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Thermal Hardening

 

The green pellets previously classified are dried and heated in the furnace grills to a temperature of 1,100ºC; they are then taken to the rotating furnace where they are finally hardened at temperatures of approximately 1,300 ºC.

 

 

 

The incandescent pellets are cooled by air flows at room temperature in the annular cooler. The hot air obtained from the heat transfer is recovered toward the rotating furnace and furnace grills.

 

 

 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Pellets Storage

 

The pellets that have been cooled and classified according to their size are sent for storage to the product yards where they are stockpiled according to their quality.

 

 

 

 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Shipment

 

The pellets are taken from the yards using basket movers and transferred by conveyor belt to the loading boom. The Guacolda II port installations permit attending ships of up to 300,000 dwt, with a loading capacity of 60,000 tons daily of pellet product.

 

 

 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Graphic Scheme

Comments are closed.