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Sintering Hematite Iron Ore

The authors investigate the influence of the basicity index CaO/SiO2 on the sintering properties of hematite ore mixtures. The experimentation was performed with three different mixtures of ores from Tazadit, Nimba, Mano-River, Itabira, Marcona, Goa, Mapawa and Cassinga. Increasing the basicity index CaO/SiO2 between 0.1 and 3, chiefly through limestone admixture makes possible to reduce the thermal consumption of sintering and to improve the physical and chemical properties of the sinter. In the case of a plant using hematite ores, it seems interesting to produce an hyperbasic sinter and to complete the blast furnace burden with calibrated ore or acid pellets.

Characteristic Data of Ores and Additive

In order to determine the effect of an increased basicity index on the sintering properties of several mixtures of hematite ores, we have considered three series of experiments:

  • The first concerned a mixture of ores from Tazadit, Nimba and Mano-River
  • The second concerned a mixture of ores from Itabira, Marcona and Mano-River.
  • The third concerned a mixture of ores from Goa, Mapawa and Cassinga.

sintering hematite screen analysis

sintering hematite grain size distribution

sintering hematite grain size
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Filter Medium in Continuous Vacuum Filtration

The filter is an apparatus designed to hold the filter medium. At such a medium takes place the entire liquid-solid or gas-solid separation process. Hence, the medium is really the essence of filtration. Yet, the medium, an originally clean porous substance with trapped solids in it, is perhaps the most neglected part of filtration research.

Basically three problems prevail at the medium:

i) Penetration of solids and their blinding of the medium and the influence of such blinding on the resistance to flow.
ii) The behavior of the medium in long term repetitive filtration.
iii) The filter effect phenomenon whereby the flow rate on filtering an apparently clear liquid through a medium decreases with time.

The Fundamental Filtration Equation

All of today’s theoretical relationships for filtration are derived from D’Arcy’s law. It was published in 1856. Essentially, it relates the flow rate to the other parameters of the system. In a modified form this relationship is given as:

dV/dt = K AP/µL…………………………………………………..(Eq. 1)

where: V = volume of filtrate
t = time
K = permeability coefficient
L = thickness of bed
A = filter area
µ = viscosity coefficient

From the above relationship a fundamental filtration equation was derived by Carman. This equation includes a term Rm for the medium

Uranium Mill Waste Disposal

The presence of radioactivity in uranium mill wastes has resulted in somewhat unique waste disposal methods. In addition to the common problems of disposing of large quantities of solid wastes, neutralizing acids, minimizing dissolved heavy metals, and clarifying all liquid effluents, the uranium mill operator must sample and analyze liquid effluents for micro-micro quantities of radionuclides such as, radium-226, thorium-230 and lead-210. Special disposal methods or decontamination procedures are required to meet the stringent limitations established by the U. S. Atomic Energy Commission on the concentration of radionuclides in liquid effluents. Routine monitoring of the receiving stream is also normally required.

Description of Liquid Wastes

Uranium extraction techniques generally involve either acid or carbonate leaching of the ores after preparation by crushing, grinding and, in some cases, roasting. Soluble uranium is recovered by ion exchange, solvent extraction, or in the case of certain alkaline leach processes by caustic precipitation. The uranium barren solutions from these uranium recovery steps make up the liquid wastes containing small amounts of radioactivity and varying amounts of dissolved solids.

The ores from which uranium is recovered in western United States contain in the order of 0.20% to 0.25% uranium oxide (U3O8) , and the radioactive materials

Underground Storage and Distribution of Hydraulic Fill

Many factors, some of which are not easily defined or described, must be considered in the design of a hydraulic backfill system. After participating in the design of several plants, I have a conviction that future refinements in sandfill systems must come in large part, from the merging of good design ideas and information from existing operating plants. It is important then, that we document and publish information on existing plant designs and their operating characteristics. This information will then be available for use by our successors and later innovators in hydraulic fill placement.

Pump Plant

The pump selected for the Mayflower Plant is a Gardner-Denver 5×6 FXG-FG duplex power pump, fitted with 3-½ inch diameter pistons and liners. It is being operated at a main shaft speed of 56 rpm. The sand slurry described is being pumped into the mine at 48 to 51% solids. Dry solid density is approximately 3.0 grams per cubic centimeter. The fluid flow from the pump to the mine is approximately 55 gallons per minute and operates at a pump discharge pressure of 500 psi. The capacity of the system is 9.7 tons of solids per hour.

As indicated in our original Plant schematic, slurry

Depressants and Flocculants in Iron Ore Beneficiation – Starches and Starch Derivatives

This article discusses the effect of physical and chemical modifications of starches on the anionic and cationic flotation of silica from oxidized iron ores and magnetite-taconite concentrates, and the results of the interaction of starch, pH, and calcium ions on the flocculation, clarification, and filtration of iron ore slimes and magnetite- taconite tailings. Starches, particularly when anionically modified, were found to be effective depressants in anionic silica flotation. British gums and dextrins were beneficial for oxidized iron ores, but none of the starches or starch derivatives appeared to have any effect on magnetite-taconite concentrates.

Anionic Silica Flotation

In the soap flotation of activated silica from iron ores a critical amount of starch addition exists beyond which flotation performance stabilizes. This critical amount of starch is dependent on the degree of grind and hence on the amount of slimes contained in the ore. With an ore sample essentially minus 325 mesh and containing approximately 50 to 55 percent iron, the critical amount of starch is about 4 lb per ton. This starch requirement contributes to a large portion of the total reagent cost, and it becomes of great interest to decrease this amount either through physical or chemical modification of the

Secondary Breakage in Taconite Open Pit Mining

The mining of taconite, to provide feed for a processing plant, requires that the flow of material continue uninterrupted. This means first, that the crude must be of a size acceptable to the primary crusher in order to reduce the delays caused by plugging the crusher with chunks. Secondly, elimination of oversize in the pit will reduce costs of all wear parts used in the mining and processing of taconite. Savings in wear parts is readily recognized in dipper teeth, bases, buckets, truck boxes, and crusher parts, both primary and secondary.

During the early days of taconite mining, it was soon recognized at reserve mining company’s Babbitt operations that experience in mining other ores was not always (or “necessarily”?) applicable to excavating taconite. This was especially true in drilling and blasting. Blasting of small tonnages in single or double rows simply filled the pit with scattered chunks and provided very shallow banks for shovel loading. It also created problems for the jet piercers, since all drilling had to be performed in fractured areas. drilling efficiency suffered and costs were extremely high. Shovel and truck efficiencies were also low and again costs were high.

The diesel track mounted crane, equipped with a drop

Use of Rocket Jet Burners in Quarrying of Granite

The first step in the quarrying of granite, following removal of any overburden material, involves the freeing of large blocks from the formation. For many years the use of explosives was the accepted method of obtaining these blocks. Even today there are operations where this is considered to be the most economical method even though it does result in a high percentage of damaged stone. In more recent times the preferred procedure at most quarries has been to produce a continuous vertical cut or slot completely around the block to be separated. Originally, this was done by drilling a series of closely spaced holes around the block and breaking the web between the holes with a chisel-like tool known as a broaching bar. The machine used in this mechanical method of producing the relief slot is known as the channel bar.

The Thermal Spalling Process

The application of a thermal device on rock depends upon a characteristic of the rock termed “spallability”. In its simplest terms spalling is considered as decrepitation resulting from differential expansion of rock crystals due to thermally induced stresses. The individual rock properties influencing the spalling characteristic are so numerous and their interaction so complex that

Radiation Logging in Leaching Studies

During the recent expansion of precipitate copper production at the Chino Mines Division of Kennecott Copper Corporation, Santa Rita, New Mexico, local studies of the dump leaching process were intensified. As these studies progressed it became apparent that a reliable method for locating leach solutions within the dump was required, since the contact between leach solutions and the copper-bearing material would determine, in great part, the recovery of values. In the past, the problem of determining leach solution contact has been attacked by various methods, including destructive testing (dump dissection), indirect observation (such as chloride or dye tracers), and mathematical or laboratory model studies. These methods have not proved completely satisfactory for the studies now being developed.

Theory

Only three of several available radiation logging techniques are currently in use at Chino.

Natural Gamma Ray Logging

Isotopes of certain elements occurring in nature are inherently unstable, and undergo spontaneous transformation to more stable forms by emission of energy in the form of a ray or particle. The most common naturally occurring isotope which decomposes by readily detectable gamma ray emission is potassium-40. Potassium tends geologically to be concentrated in clay minerals (such as illite), their parent minerals (orthoclase feldspars and micas), and

Priming and Boostering Anfo with Slurry Explosives

Following the wide-spread acceptance of ANFO as a useful, low cost blasting agent, studies have been made to adequately describe the physical and explosive properties of this material. As the quality of the AN blasting prill improved, reliability and sensitivity to initiation were greatly increased and many methods of priming were chosen from the standpoint of economics with little appreciation for the need to initiate so as to obtain the most efficient detonation. Under certain conditions, ANFO could be initiated with primers no more powerful than a No. 8 blasting cap.

It is the nature of ANFO to demonstrate transient velocities upon initiation from any primer or booster. These transients are a function of the primer performance and in order to obtain the most efficient use of ANFO the principles involved in priming should be considered. The principles involve not only power output but also geometry and can be summarized as follows:

A primer or booster for ANFO should have:

  1. High detonation pressure
  2. No dual or low order velocity
  3. Adequate diameter and length

Ammonium nitrate-fuel oil mixtures are extremely susceptable to transient velocities upon initiation from a primer. Initial velocities in ANFO over the range of 2,000 to 20,000 fps have been observed

Flow of Solids in Bins

There used to be a time when bins were designed for total volume and placed in any available place of the plant. Poke holes were provided and feed was maintained by manual prodding, lancing, hammering, and by various mechanical flow-promoting devices. Little thought was given to what occurred inside the bins and why materials did not flow. Indeed, such mental effort was hard to justify while low-cost manual labor was plentiful, quality standards low, and rates of feed moderate.

Typical Storage and Flow Problems

In order to design an efficient storage plant or contact-bed reactor it is necessary to be aware of the problems which can arise in flow and storage. The typical problems are:

No flow: a stable arch (dome) or rathole develops within the solid and flow ceases.

Erratic flow: momentary arches form within the solid; ratholes empty out partly or completely, then collapse. Density of the stream swings within wide limits.

Flashing: powders in erratic flow aerate, fluidize and flush. While air-locks can be used to prevent flushing they do not eliminate erratic flow.

Insufficient flow: the volumetric rate of gravity flow through an orifice depends on the stored solid. Coarse dry solids flow at a high rate, closely approaching the

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