Review of organic binders for iron ore concentrate agglomeration

Mineral Processing and Extractive Metallurgy Review

et al. 2015

Iron ore pellets abrade during handling and produce dust. This study was conducted to determine what factors affect pellet dustiness, and whether dustiness can be related to the abrasion index. Factors studied included bed depth within a straight grate furnace; pellet chemistry; firing temperature; coke breeze addition; and tumble index. Abrasion indices for all pellet samples ranged from 1.9-5.0% (20 samples) and from 7.1-27.5% (5 samples). Pellets were dropped in an enclosed tower, which enabled the collection of airborne particles generated during pellet breakdown. The quantity of airborne particles generated by each pellet type was 10-100 mg= kg-drop, or 50-500 mg=kg over five drops through the tower. Pellet dustiness was predominantly affected by pellet chemistry and by pellet firing temperature. Results showed a nearly 21% increase in dustiness for every percent decrease in firing temperature -this was based on a typical firing temperature of 1280 C. Pellet dustiness was regressed to the pellet abrasion index (for AI < 5%), which yielded a correlation coefficient of 0.22. These results show that, although AI is one of the best indicators of fired pellet quality and can indicate high levels of dust, it could not explain the dustiness of good quality pellets.The second paper (Iron Ore Pellet Dustiness Part II) explains the relationship between AI and dust for good-quality pellets; and compares fines generation between pellets fired in Straight-Grate (Traveling Grate) and Grate-Kiln furnaces.

Section: Iron Ore Agglomerationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Iron Ore Pellet Dustiness Part I: Factors Affecting Dust Generation

Halt

Nitz

Mineral Processing and Extractive Metallurgy Review

et al. 2015

“…These occurrences could lead to similar levels of dust formation across a wide range of abrasion indices, which would explain the poor correlation observed in part I of this paper (Halt and Kawatra, 2014). This thought led us to examine how pellet abrasion resistance and the fines size distribution are related.…”

Section: Abrasion Resistance Of Iron Ore Concentrate Pelletsmentioning

confidence: 80%

“…As an example, final green-ball moisture ranged from 8.5 to 10% (wet basis) for those samples, which would tend to affect final pellet porosity. Increased pellet porosity, and the loss of additional inorganic material due to organic binders have been the major reported drawbacks to organic binder use (Halt and Kawatra 2014).…”

Section: Effects Of Binders On Abrasion Indexmentioning

confidence: 99%

Iron Ore Pellet Dustiness Part II: Effects of Firing Route and Abrasion Resistance on Fines and Dust Generation

Halt

Mineral Processing and Extractive Metallurgy Review

2014

Iron ore pellets abrade during their production and handling, which lowers product quality and leads to dustiness issues. Pellets were collected from a variety of plants (operating either Straight-Grate (SG) or Grate-Kiln (GK) furnaces) to understand whether furnace type affects fines and dust formation. Results showed that pellets fired in SG furnaces were less abrasion-resistant (3.5 Â lower) than pellets fired in GK furnaces. Concurrently, laboratory pellets were prepared using various ores, binders, and firing temperatures. These were tested to understand the relationship between abrasion index and dustiness. AI was observed to range from 1 to 14%. Dustiness, determined via AI and size distributions of abrasion progeny, ranged from 0.2 to 1.6%. For AI greater than 5%, AI can be used to indicate potentially high levels of dust. For AI less than 5%, there was a poor correlation between AI and dustiness. This was explained by the observation that as AI decreased, the abrasion product fineness increased. The results from parts I and II of this investigation suggest that material loss and levels of pellet dustiness may be significantly affected by pellet quality up to a certain point. Poorly fired pellets will be dusty during handling and transportation, while well-fired pellets will generate less -but finer -material as their quality improves. This could lead to little observed changes in dust generation over a wide range of pellet quality. Dust generation at each site would then depend on the quantity of material produced and their extent of handling.

“…There are very few processes that can be used to concentrate this type of ore. As the magnetite ore grade continues to decline and the depth at which the magnetite must be mined increases, mining and concentrating hematite will become necessary to meet consumer demand. With this in mind, there has been a large increase in iron ore processing research (Bolen 2014;Kawatra 2008, 2013;Halt et al 2014, Halt andHaselhuhn 2012Haselhuhn , 2013aLiu et al 2014;Manouchehri 2014;Sandvik and Larsen 2014;Semberg et al 2014).…”

Section: Introductionmentioning

confidence: 97%

Effects of Water Chemistry on Hematite Selective Flocculation and Dispersion

Haselhuhn

Mineral Processing and Extractive Metallurgy Review

2014

The only industrially proven method for the beneficiation of fine-grained (<25 mm) hematite ores is selective flocculation and dispersion desliming followed by reverse cationic flotation. This process is reliant upon both water chemistry and proper reagent selection and dosing for effective separation of the hematite from gangue minerals. This study was performed to assess the effects of water chemistry on the beneficiation process in a pilot-scale deslime thickener. Grade versus recovery curves were constructed at varying water chemistries. In each set of experiments the concentration of one water chemistry parameter was varied while all others were held constant. The varied parameters included pH, sodium concentration and calcium concentration.The optimal pH for the separation of hematite from silica was found to be around 10.5. This was hypothesized to be due to a maximization in starch selective adsorption. Minimization in the sodium concentration showed increases in both the grade and the recovery of iron. Minimization in the calcium concentration showed increases in the grade of iron but losses in the recovery of iron. This study showed that the most effective way at increasing both the grade and recovery of the process was to optimize the pH and minimize the sodium concentrations.