New process for treating boron-bearing iron ore by flash reduction coupled with magnetic separation

Boron is an important industrial raw material often sourced from minerals containing different compounds that cocrystallize,which makes it difficult to separate the mineral phases through conventional beneficiation.This study proposed a new treatment called flash reduction-melting separation(FRMS)for boron-bearing iron concentrates.In this method,the concentrates were first flash-reduced at the temperature under which the particles melt,and the slag and the reduced iron phases disengaged at the particle scale.Good reduc-tion and melting effects were achieved above 1550℃.The B_(2)O_(3) content in the separated slag was over 18wt%,and the B content in the iron was less than 0.03wt%.The proposed FRMS method was tested to investigate the effects of factors such as ore particle size and tem-perature on the reduction and melting steps with and without pre-reducing the raw concentrate.The mineral phase transformation and morphology evolution in the ore particles during FRMS were also comprehensively analyzed.

Phosphorus reduction behavior of high-phosphate iron ore during hydrogen-rich sintering

High-phosphorus iron ore resource is considered a refractory iron ore because of its high-phosphorus content and complex ore phase structure. Therefore, the development of innovative technology to realize the efficient utilization of high-phosphorus iron ore resources is of theoretical and practical significance. Thus, a method for phosphorus removal by gasification in the hydrogen-rich sintering process was proposed. In this study, the reduction mechanism of phosphorus in hydrogen-rich sintering, as well as the reduction kinetics of apatite based on the non-isothermal kinetic method, was investigated. Results showed that, by increasing the reduction time from 20 to 60 min, the dephosphorization rate increased from 10.93%to 29.51%. With apatite reduction, the metal iron accumulates, and part of the reduced phosphorus gas is absorbed by the metal iron to form stable iron-phosphorus compounds, resulting in a significant reduction of the dephosphorization rate. Apatite reduction is mainly concentrated in the sintering and burning zones, and the reduced phosphorus gas moves downward along with flue gas under suction pressure and is condensed and adsorbed partly by the sintering bed when passing through the drying zone and over the wet zone. As a result, the dephosphorization rate is considerably reduced. Based on the Ozawa formula of the iso-conversion rate, the activation energy of apatite reduction is 80.42 kJ/mol. The mechanism function of apatite reduction is determined by a differential method (i.e., the Freeman-Carroll method) and an integral method (i.e., the Coats-Redfern method). The differential form of the equation is f(α)=2(1-α)^(1/2), and the integral form of the equation is G(α)=1-(1-α)^(1/2).

Analysis of gas-solid flow and shaft-injected gas distribution in an oxygen blast furnace using a discrete element method and computational fluid dynamics coupled model

lronmaking using an oxygen blast furnace is an attractive approach for reducing energy consumption in the iron and steel industry. This paper presents a numerical study of gas-solid flow in an oxygen blast fur- nace by coupling the discrete element method with computational fluid dynamics. The model reliability was verified by previous experimental results. The influences of particle diameter, shaft tuyere size, and specific ratio （X） of shaft-injected gas （51G） flowrate to total gas flowrate on the SIC penetration behavior and pressure field in the furnace were investigated. The results showed that gas penetration capacity in the furnace gradually decreased as the particle diameter decreased from 100 to 40 mm. Decreasing particle diameter and increasing shaft tuyere size both slightly increased the SIG concentration near the furnace wall but decreased it at the furnace center. The value of X has a significant impact on the SIG distribution. According to the pressure fields obtained under different conditions, the key factor affecting SIG penetration depth is the pressure difference between the upper and lower levels of the shaft tuyere. If the pressure difference is small, the SIG can easily penetrate to the furnace center.

Observation of viable alloskin vs xenoskin grafted onto subcutaneous tissue wounds after tangential excision in massive burns

Background:Staged excision and grafting with viable cryopreserved alloskin or fresh pigskin at an early stage is a main strategy for wound management in massive burns.Alloskin is the gold standard of a biological temporary skin substitute,and the main drawback to its wider use is the limited number of donors.In this paper,we compare the use of fresh pigskins to cryopreserved alloskins as temporary skin substitutes on subcutaneous tissue wounds after tangential excision by observing the clinical performances of these grafts in cases of a massive burn.Methods:We selected six adult massive burn patients undergoing tangential excision and skin grafting on subcutaneous tissue wounds(TESGSTW)at our burn center from January 1,2003 to December 31,2013.The general clinical data and survival percentage of skins at postoperative weeks(POWs)1,2,and 3 were analyzed.In our clinical practice,we also observed the phenomenon that several viable cryopreserved alloskin or fresh pigskin grafts used as temporary coverage on subcutaneous tissue wounds had long-term survival after repeated desquamation.The macroscopic and histological results of one typical case were also analyzed.Results:In this study,the first three TESGSTW operations were performed at 2–3,5–8,and 11–16 days post-injury.The operation areas were 30.3±7.9%total body surface area(TBSA),19.0±6.0%TBSA,and 12.0±1.7%TBSA,respectively.The survival percentage of the cryopreserved alloskins or fresh pigskins at POWs 1,2,and 3 were 80.0±10.0%vs 75.7±5.3%(t=1.01,P=0.16),71.2±10.6%vs 66.4±6.2%(t=1.09,P=0.30),and 48.7±2.5%vs 35.0±7.0%(t=3.83,P=0.03),respectively.The microscopic observation of the survival of alloskins or pigskins in one typical case showed rete ridges and a basilar membrane at the joint of the epidermis and dermis at an early stage;these structures disappeared with extended time post-operation.Conclusions:From the clinical observations,fresh pigskin and cryopreserved alloskins could be used with equal effectiveness at an early stage(within 2 weeks post-operation)as temporary coverage on massive burns after TESGSTW.After engraftment,several cryopreserved alloskins or fresh pigskins could co-survive in a massive burn patient for an extended amount of time.The co-survival of alloskin and pigskin will provide clues for further research into skin transplantation.